My Ritetemp model 8035c thermostat all of a sudden stopped displaying current room temperature in the main screen (middle). It displays only C or F up to 0 degrees or 32 degrees now. Every time the heat comes on it continues to run unless I manually shut it off. I've tried resetting but no results. Any help would definitely be welcomed.

Sounds like you might have a bad thermostat.
Next time but a Honeywell.