When trying to troubleshoot doorbell problems, the trouble may be as simple as a tripped circuit breaker. The circuit breaker feeds a transformer that feeds a button that in turn feeds the bell that rings when someone pushes the button. Simply check the incoming power with a volt meter, tick-tracer, or multimeter.
Safety first! Look to see if the circuit breaker is in the tripped position. If so try resetting it and then check the buttons to see if the doorbell rings. If not, turn off the power to the door bell and disconnect the hot and neutral wires from the doorbell transformer. Leave the wires hanging where they are not touching anything and turn on the circuit again. Now, use a voltage tester to see if there is 120 volts on the wires. If so, the feed is good. If you don't have power here, either the circuit breaker is bad or the wiring from the circuit breaker to the transformer has a problem. You may have to remove and install a circuit breaker.
