Just to be technically clear - If it was your only copy of those files then it wasn't a backup. A backup is a second (or more) copy of a file. I suggest a minimum of 3 copies to my customers, this way when your drive fails you still have a copy of your important files and a backup copy. Rule#1 is "Never trust your important files to a single device" and if you only have 1 backup then when your drive fails it leaves you in violation of Rule#1. Notice I said 'when your drive fails'. All drives fail; don't trust them.
Let us know if you get your files back or not. It might help someone else in the future.