Troubleshoot a garbage disposal by first checking the reset button, trying to get the grinder wheel to turn, and checking the appliance's power supply. Most garbage disposals have a reset button on the bottom of the device that pops out when the motor overheats or becomes electrically overloaded. Pushing the reset button back into its housing resets the disposal.
Disconnecting the garbage disposal from its power supply is essential before attempting to clear a stuck grinder wheel. Beginning work without disconnecting the power puts you at significant risk of electric shock or other physical injury. Most garbage disposals have dedicated circuit breakers that make disconnecting the devices easier. Inspecting the breaker also shows you whether the garbage disposal's circuit overloaded and tripped the breaker.
Many garbage disposals come with a large hex wrench that fits into a special housing on the bottom of the appliance. Inserting the wrench into the housing and turning it several times often dislodges any stuck matter and frees the grinding wheel.
If a garbage disposal does not have a hex wrench housing, physically clearing a jam is still possible. Using two broom handles or similar long, sturdy rods, insert the rods into the drain at opposing angles to each other. Turning the rods in a full circle can sometimes dislodge a jam or clog in the grinding wheel.