Clothes Dryer will not heat up
probably a bad circuit breaker, recommend replacing it.  You can check if it is bad by checking the voltage on it using an ohm meter.  Set the ohm meter to 200v ac, touch one probe to the screw where the wire is attached and the other probe to the silver grounding bar with all the bare copper wires attached.  It should read approx 120v.  Check both wires this way.  Start the dryer, if it doesn't have heat again... recheck the voltage on the breaker again.  I'm betting that one of the screws shows 0 voltage... my guess is that one leg of your breaker is bad or faulty.