Restoring my computer

I have a Dell XPS desktop that has a backup image on it that was installed by Dell; I cannot restore it with the Ctrl - F11 function key.  With Norton Ghost I can see it,  that it’s there on the C: drive, as DellRestore Fat32, Primary –Bootable. I want to restore my system back to factory specs. Does any out there know how I can do this??  rj