likely your cluster has failed and you need a new either entire screen or whole new unit. Call United Radio and they can likely set you up with a new cluster with the appropriate milage for you.
I actually lost the HVAC controls also. But when I disconnected the battery over night they started working again. My radio is fine. Everything on the radio stack works. I have a speedometer and a tach, Nothing else. The screen glows a very faint blue that you can see at night. Nothing else.