touch manual file:
-B, --backward=SECONDS
Modify the time by going back SECONDS seconds. For example,
touch -r foo -B 5 bar will make the file bar 5 seconds older than file foo.
Never had to fix a mess like that, but touch might work if it's unix/linux based. I think a day is 86,400 seconds....
I once did a [ chown -r user:grp .* ] in /home as root
This has the effect of making all directories owned by one user and group..... oops

I hate it when my own stupidity makes me work late.