Project not in database

A project in my folder was copied for someone else to work on and somehow they remained linked meaning that when he deleted his copy it also deleted the original. Within project manager it now says the project is not found in the database. The pages are still there via windows explorer and can still be opened but not via project manager. Our IT system does have a back up but rather than restoring the whole database I was wondering if anyone can tell me which part of the database is causing this problem so we can just restore the relevant parts?