One of them might have tripped and cut off the power the thermostat. If this doesnt work then the issue with the thermostat could come from loose connections or other wiring problems.

Why Is My Thermostat Blank Heating Cooling Service
Thermostat display not working. For an air conditioner the problem might be the safety switch installed in the drain pan activating because of an overflow. 4 reasons your thermostat display is not working and how to fix it 1. No indication on display. Some thermostats allow users to adjust the displays brightness. In some homes an air conditioner or furnace can trigger a safety switch and turn off the thermostat entirely if any damage has been detected. Change the batteries to see if this restores the thermostat screen.
If your thermostat screen has gone blank and your thermostat runs on batteries the first thing you should try is replacing the batteries with a fresh set. A blank thermostat is one of the most common calls we get and is a sign that your heating and air system is having an issue. If you would like to get a quick rundown of the top three things you can. If you see a red light blinking in the upper part of the display the battery is low and being. If you see a green light blinking in the upper part of the display your thermostat is starting. Lcd brightness display is too low.
Thermostat batteries died and need to be replaced if your thermostat is blank the first thing you should do is check the batteries. Indoor temperature display is incorrect. Nest thermostat not functioning red light blinking. Depending on the model of your ac. 1 indoor temperature display needs calibrating always allow 1 hour before calibrating after any power cycle 1 calibrate indoor temperature sensor. If your thermostat is wired directly into your homes electrical system a blank screen indicates there is no power going to the unit which means there may be a tripped breaker or a problem with.
You may want to laugh or roll your eyes at this one but unless you live by yourself its. 1 check wiring between r c. 2 check transformer for 24vac output. The safety switch was triggered. Somebody turned it off. If the thermostat runs from the houses electrical system check on the circuit breakers.
3 check for broken or shorted thermostat wire. There may be a problem with the air conditioner or heater that has caused the transformer to stop sending voltage to run the thermostat.