The most likely culprit of a conked-out garbage disposal is a clog, either near the sink blades or at the base of the disposal. Turn off the disposal and inspect the blades, using a long stick to dislodge stuck foods or utensils. (Never insert your hand into the disposal!) If the blades aren't the culprit, locate the bottom of the disposal underneath the sink, and wiggle it back and forth with an Allen wrench to dislodge any stuck objects. If it turns out that you don't have a clog on your hands, it's possible that the circuit breaker has simply tripped, in which case you should be able to depress the red button at the bottom of the disposal to restore power and operation.