Here is the script allowing you to check the integrity of your site's files.
Site File Checker script will help you to know, that all of files on your site was not changed without your notice, that they don't contain any virus, exploit or backdoor inserts. Script will count checksums of all of your files situated in the script root directory and also in nested directories. Then script will also save all last change timestamps of files.
While checking, the script will show directory changes (it will show new ones and deleted), file changes (it will display deleted, created and modified files).
It is recommended to remove the script from your server each time you create checksums to make it safe to hacker's changes.
Before the first use, open the script in the notepad and edit your administrator's login and password.
The script can be downloaded here.