Columns are numbers instead of letters

Hi there,

I found this link to an answer but it was related to Excel 2003 and the answer works. But I am using the newer Excel so the same answer can't help me.

http://www.excelforum.com/excel-gene...o-numbers.html

How do I change the columns back to letters.. it's extremely annoying and I have no idea how this happened in the first place!

Thanks