If you need to find what files have been changed on your website by another developer, automated update or hacker then you can use these commands via SSH to see what has chnaged.
find . -mtime -3Find files modified in the last 3 days
find . -ctime -3Find files with changed times in the last 3 days
find . -ctime +1 -a -ctime -3Find files changed between date ranges.
Which will find all files changed, and thus modified, at least one day ago but within three days ago.