display days of a month

Try this, copied across...
=DATEVALUE(1&"/"&COLUMN(A1)&"/"&2015)

Format as date

Maybe:
put a date in A1 (now you have a serial number underneath the cell i.e. 1/1/2015 is 42032)
now you need to custum number formatting
open the format cell dailog box and insert just the letter M wich means mounth (be carfull tha you will see 1 but underneath you have 42032 that's the real number that Excel make calculation)
in B1 make this formula =A1+31

<table border="1" cellspacing="0" cellpadding="0" style="font-family:Calibri,Arial; font-size:14pt; background-color:#ffffff; padding-left:2pt; padding-right:2pt; "> <colgroup><col style="width:30px; " /><col style="width:37.6px;" /><col style="width:37.6px;" /><col style="width:37.6px;" /><col style="width:37.6px;" /><col style="width:37.6px;" /><col style="width:37.6px;" /><col style="width:37.6px;" /><col style="width:37.6px;" /><col style="width:37.6px;" /><col style="width:37.6px;" /><col style="width:37.6px;" /><col style="width:37.6px;" /></colgroup><tr style="background-color:#cacaca; text-align:center;font-size:8pt; "><td > </td><td style=" border-width:3px; border-style:solid;border-color:#f0f0f0; ">A</td><td style=" border-width:3px; border-style:solid;border-color:#f0f0f0; ">B</td><td style=" border-width:3px; border-style:solid;border-color:#f0f0f0; ">C</td><td style=" border-width:3px; border-style:solid;border-color:#f0f0f0; ">D</td><td style=" border-width:3px; border-style:solid;border-color:#f0f0f0; ">E</td><td style=" border-width:3px; border-style:solid;border-color:#f0f0f0; ">F</td><td style=" border-width:3px; border-style:solid;border-color:#f0f0f0; ">G</td><td style=" border-width:3px; border-style:solid;border-color:#f0f0f0; ">H</td><td style=" border-width:3px; border-style:solid;border-color:#f0f0f0; ">I</td><td style=" border-width:3px; border-style:solid;border-color:#f0f0f0; ">J</td><td style=" border-width:3px; border-style:solid;border-color:#f0f0f0; ">K</td><td style=" border-width:3px; border-style:solid;border-color:#f0f0f0; ">L</td></tr><tr style="height:21px ;" ><td style="border-width:3; border-style:solid;border-color:#f0f0f0; background-color:#cacaca; text-align:center; " >1</td><td style="text-align:right; ">1</td><td style="text-align:right; ">2</td><td style="text-align:right; ">3</td><td style="text-align:right; ">4</td><td style="text-align:right; ">5</td><td style="text-align:right; ">6</td><td style="text-align:right; ">7</td><td style="text-align:right; ">8</td><td style="text-align:right; ">9</td><td style="text-align:right; ">10</td><td style="text-align:right; ">11</td><td style="text-align:right; ">12</td></tr></table><br /><table style="font-family:Arial; font-size:10pt; border-style: groove ;border-color:#00ff00;background-color:#fffcf9; color:#000000; "><tr><td ><b>Spreadsheet Formulas</b></td></tr><tr><td ><table border = "1" cellspacing="0" cellpadding="2" style="font-family:Arial; font-size:9pt;"><tr style="background-color:#cacaca; font-size:10pt;"><td >Cell</td><td >Formula</td></tr><tr><td >B1</td><td >=+A1+31</td></tr></table></td></tr></table> <br />Excel tables to the web - Excel Jeanie Html 4

Gerry, perhaps you missed ths part?

When month name is put in cell A1,

Click to expand...

@FDibbins
Opppsss!! you are right
english is not my first lenguage...somtimes i miss somethings
Thank you

No problem, we all miss things

I just noticed that I had day/month swapped around anyway...
=DATEVALUE(COLUMN(A1)&"/"&$A$1&"/"&2015)

However, if the OP uses my suggestion in B1, modified to...
=DATEVALUE(1&"/"&$A$1&"/"&2015)
Then uses your suggestion for all subsequent cells, we have teh best of both worlds

It doesn't work, once again the requirement is, if put January in cell A1, the dates 1,2,3....31 should be displayed in cell B1 to AF1 and if April is put it should display 1,2,3...30 like that. Please help.

Assuming the spelled out month name is in cell A1, put the numbers 1, 2, 3,...,27,28 in cells B1:AC1, then put these formulas in the indicated cells...

AD1: =IF(MONTH(0+(28&A1&YEAR(NOW())))=MONTH(1+(28&A1&YEAR(NOW()))),29,"")

AE1: =IF(AD1="","",AD1+1)

AF1: =IF(ISNUMBER(SEARCH(LEFT(A1,3),"Jan Mar May Jul Aug Oct Dec")),AE1+1,"")

thank you, it works well.

Unfortunately it doesn't work for leap year. Could you modify the formula in AD4 to display 29 for February in a leap year.

thanks