Excel 2007 : Number formatting

[redroses15]

Can't believe the trouble I am having with Excel 7, when I go into a sheet and go to a cell and put in a number then tab to next cell the number reverts back to zero.
I have gone into format , numbers and the only way it will let me enter a number into a cell is to enter the text category, but this problem is happening in other excel worksheets that have been saved. I went to do Petty Cash and had to enter how many $ notes were needed and each time I entered a number then tab to next cell the number reverted back to a zero.
I think that maybe someone has done something in Excel but I can not work out what it is or how to fix the problem. I am finding I am having a lot of problems with this version, my old version 2003 seems to be a lot easier.
Thank you

[teylyn]

Hello redroses,

this sounds very frustrating. Can you post the workbook in question? Delete all but a few rows, replace real names with dummy data and then attach the file.

cheers

[redroses15]

I will see if I can, the problem is that it is from my computer at work, but I will try, thank you Teylyn