Dim FieldNum As Long
FieldNum = Application.InputBox(Prompt:= _
"Please Enter the Number of the column that you wish to Filter.", _
Title:="SPECIFY COLUMN", Type:=1)
If FieldNum > 0 Then
w.Range("A1").AutoFilter field:=FieldNum, _
Criteria1:=CStr(availableFilters(currentFilterIndex))
End If