Need Thermostat Help

Had a new A/C unit installed in summer. Everything worked fine but when winter came the heat won’t kick on, just blows room temperature air. The tech who installed the a/c had messed with the thermostat wires. The tech who later came said the wires needed to be changed but he would have to go find a manual. He ended up being a no call, no show for two appointments after. Anyone in here able to help me figure it the wiring?