It really depends on the data and how you've populated the the combobox.
If your ids where in A2:A20 and you populated the combobox using that range then the ListIndex of the selected item would correspond to the row number.
For example if you picked, from the combobox, the 4th item in the list the ListIndex would be 3.
To get the row number on the worksheet just add 2.
Probably not a good explanation, see if this helps.
1 Create a list like this starting in A1 on a worksheet called Data.
<TABLE style="WIDTH: 105pt; BORDER-COLLAPSE: collapse" border=0 cellSpacing=0 cellPadding=0 width=140><COLGROUP><COL style="WIDTH: 48pt" width=64><COL style="WIDTH: 57pt; mso-width-source: userset; mso-width-alt: 2779" width=76><TBODY><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #4f81bd 0.5pt solid; WIDTH: 48pt; FONT-FAMILY: Arial; BACKGROUND: #4f81bd; HEIGHT: 12.75pt; COLOR: white; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 700; BORDER-RIGHT: #f0f0f0; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none; mso-pattern: #4F81BD none" class=xl65 height=17 width=64>IDS</TD><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; WIDTH: 57pt; FONT-FAMILY: Arial; BACKGROUND: #4f81bd; COLOR: white; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 700; BORDER-RIGHT: #4f81bd 0.5pt solid; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none; mso-pattern: #4F81BD none" class=xl65 width=76>FirstField</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #4f81bd 0.5pt solid; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; HEIGHT: 12.75pt; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #f0f0f0; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65 height=17>ID1</TD><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #4f81bd 0.5pt solid; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65>Data1</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #4f81bd 0.5pt solid; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; HEIGHT: 12.75pt; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #f0f0f0; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65 height=17>ID2</TD><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #4f81bd 0.5pt solid; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65>Data2</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #4f81bd 0.5pt solid; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; HEIGHT: 12.75pt; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #f0f0f0; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65 height=17>ID3</TD><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #4f81bd 0.5pt solid; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65>Data3</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #4f81bd 0.5pt solid; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; HEIGHT: 12.75pt; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #f0f0f0; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65 height=17>ID4</TD><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #4f81bd 0.5pt solid; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65>Data4</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #4f81bd 0.5pt solid; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; HEIGHT: 12.75pt; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #f0f0f0; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65 height=17>ID5</TD><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #4f81bd 0.5pt solid; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65>Data5</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #4f81bd 0.5pt solid; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; HEIGHT: 12.75pt; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #f0f0f0; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65 height=17>ID6</TD><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #4f81bd 0.5pt solid; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65>Data6</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #4f81bd 0.5pt solid; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; HEIGHT: 12.75pt; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #f0f0f0; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65 height=17>ID7</TD><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #4f81bd 0.5pt solid; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65>Data7</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #4f81bd 0.5pt solid; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; HEIGHT: 12.75pt; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #f0f0f0; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65 height=17>ID8</TD><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #4f81bd 0.5pt solid; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65>Data8</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #4f81bd 0.5pt solid; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; HEIGHT: 12.75pt; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #f0f0f0; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65 height=17>ID9</TD><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #4f81bd 0.5pt solid; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65>Data9</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #4f81bd 0.5pt solid; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; HEIGHT: 12.75pt; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #f0f0f0; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65 height=17>ID10</TD><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #4f81bd 0.5pt solid; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65>Data10</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #4f81bd 0.5pt solid; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; HEIGHT: 12.75pt; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #f0f0f0; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65 height=17>ID11</TD><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #4f81bd 0.5pt solid; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65>Data11</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #4f81bd 0.5pt solid; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; HEIGHT: 12.75pt; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #f0f0f0; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65 height=17>ID12</TD><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #4f81bd 0.5pt solid; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65>Data12</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #4f81bd 0.5pt solid; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; HEIGHT: 12.75pt; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #f0f0f0; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65 height=17>ID13</TD><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #4f81bd 0.5pt solid; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65>Data13</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #4f81bd 0.5pt solid; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; HEIGHT: 12.75pt; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #f0f0f0; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65 height=17>ID14</TD><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #4f81bd 0.5pt solid; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65>Data14</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #4f81bd 0.5pt solid; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; HEIGHT: 12.75pt; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #f0f0f0; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65 height=17>ID15</TD><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #4f81bd 0.5pt solid; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65>Data15</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #4f81bd 0.5pt solid; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; HEIGHT: 12.75pt; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #f0f0f0; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65 height=17>ID16</TD><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #4f81bd 0.5pt solid; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65>Data16</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #4f81bd 0.5pt solid; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; HEIGHT: 12.75pt; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #f0f0f0; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65 height=17>ID17</TD><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #4f81bd 0.5pt solid; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65>Data17</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #4f81bd 0.5pt solid; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; HEIGHT: 12.75pt; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #f0f0f0; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65 height=17>ID18</TD><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #4f81bd 0.5pt solid; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65>Data18</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #4f81bd 0.5pt solid; BORDER-LEFT: #4f81bd 0.5pt solid; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; HEIGHT: 12.75pt; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #f0f0f0; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65 height=17>ID19</TD><TD style="BORDER-BOTTOM: #4f81bd 0.5pt solid; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent; FONT-FAMILY: Arial; COLOR: black; FONT-SIZE: 10pt; BORDER-TOP: #4f81bd 0.5pt solid; FONT-WEIGHT: 400; BORDER-RIGHT: #4f81bd 0.5pt solid; TEXT-DECORATION: none; text-underline-style: none; text-line-through: none" class=xl65>Data19</TD></TR></TBODY></TABLE>
2 Now create a userform, add a combobox and a textbox.
3 Add this code to the userform module.
Code:
Option Explicit
Private Sub ComboBox1_Change()
If ComboBox1.ListIndex <> -1 Then
TextBox1.Value = Range("A" & ComboBox1.ListIndex + 2).Offset(, 1)
End If
End Sub
Private Sub UserForm_Initialize()
ComboBox1.List = Worksheets("Data").Range("A2:A20").Value
End Sub
Now when you run the userform and select an ID from the combobox the corresponding data from the next column should appear in the textbox.