Will a stuck thermostat unstick itself?

No, an electronically stuck wall thermostat or a mechanically stuck thermostat switch will almost never unstick itself once the internal contacts have fused or physical components have seized. In electronic thermostats, electrical arcing or power surges can permanently weld relay switch contacts closed, causing a continuous 24-volt call for heating or cooling that will run your HVAC system indefinitely until manually interrupted. Similarly, mechanical valves or wax pellets in cooling thermostats that jam due to corrosion or wear require manual cleaning, repair, or full replacement. Relying on a stuck thermostat to fix itself will result in extreme indoor temperatures and high utility bills. You can troubleshoot by removing the thermostat faceplate; if the HVAC equipment stops instantly, the switch is permanently fused. You can verify resolution when you replace the faulty thermostat.