restoring workbooks from a previous day

[rayray21]

i had a co-worker crash everything i did to our sample workbook. Is there any way to restore from a previous day before he came in? say 7/27/2012 at 12:00 pm, noon?

[vlady]

if you have a backup copy .bak / .xlt

--but if you don't , Excel alone can't do that...