One possible solution is to check previous versions of the folder that are regularly archived in the system, usually they’re made once a day at midnight and two within the last couple hours of checking. Simply go to the left hand options of the folder, click on previous versions of the file/folder, and find the date you’re looking for. You can copy or restore the files you find there.
If it was deleted from a workstation rather than the server, you will need to restore from your backup if you have any. If you don’t have backup well start praying and get the person who deleted the files to start typing.
One thing to consider is also asking the person who originally created the file to see if they have a backup or a local copy.
There are files out there that give you a chance of recovering deleted files, but each write to the disk since the file was deleted can reduce the chances of recovering the file intact. I have had good lucks in the past with these applications though. A Google search of “undelete files windows” will yield you a good amount of pages to go through, but one I’ve used previously costs around $50.