Dunno if I understood your question right, but anyway try below.

Find no of days difference (Difference.Days=Current.Date-Search.Date [E.g, No.of.days.difference between 20060525 and 20060520 is 5]). Say you wanna search your file in a directory called "XXX" exactly 5 days before.

find XXX -mtime 5 -depth -type f

The above command will list you all files in XXX modified 5 days before.

Karthik