File Storage Best Practices
ILR Tech Services strongly recommends saving files to your My Documents folder or your shared drives. These storage locations are automatically backed up and thus can be more easily recovered in the event of a hardware failure.
Did you delete a file/folder or did you save a file and replaced a version that you want back?
http://windows.microsoft.com/en-US/windows7/previous-versions-of-files-frequently-asked-questions