The heater was working fine yesterday morning. Last night when I returned home, it was freezing. Nothing will work - not the heater, the air conditioner or fan. There eis not even a clicking noice at the thermostat when I turn it up, down, from one function to another. I flipped the breaker in the breaker box and also the breaker on the actual inside unit. Any suggestions?

How do I know if the problem is in the thermostat? (https://www.askmehelpdesk.com/heating-air-conditioning/heating-cooling-maintenance-repair-troubleshooting-frequently-asked-questions-58313.html#post268203)