A server with multiple users will probably have the old bits on the disk over written very quickly making recovering most files impossible. Are you certain the user actually deleted the file and didn't "recycle" it. Some users don't know the difference.
Performing daily backups would be a good idea, allowing you to restore files over a day old which were accidentally deleted.
You didn't indicate the filesystem used on the server. The "debugfs" program may allow you to list deleted inodes and recover the files. There are some forensic type programs, like scandisk or photorec. These tools should be used in single user mode however, taking the samba server offline. The results may be recovered files in another directory named by their old inode numbers.
It would be best to educate the users to be careful deleting files. You could try changing the settings of the file browsers so that delete doesn't show up in the context menus.
If the files being deleted are not owned by the people deleting the file, you should set the sticky bit on the directory containing the files. This prevents deletion by non-owners of the file.
Last edited by jschiwal; 12-28-2010 at 09:13 AM.