Problem with a/c & heat thermostat

Someone in my house knocked the thermostat loose from the wires I bought a new one, the same type, connected it and it will not go on. It will not call for heat. Don't know what to do now. Can anyone suggest anything?

Post your wiring configuration you are using and what kind of system you have.

Unit worked fine until it was hit? How hard were the wires pulled on?

You can break a wire and not know it because the color jacket will hide the broken wire. You can trace the wires from the thermostat and use a meter to sound them out.

If you or someone you know is handy with a multimeter its not too hard to trace down the fault.