Sounds like your display is out.
If it was an issue of your unit losing power and then needing a code, you wouldn't get any sound and you'd have to input a code before anything would work..
-Visit your local car audio dealer and see if they can send your unit out for repairs
-I don't recommend visiting the dealership to get a new one or to get it repaired, but its an option (dealerships usually overcharge)
-I think the less expensive, and better alternative is for you to just go purchase an aftermarket radio and get it installed or find a working factory unit on Ebay and get it swapped out.