Do you have a non-functioning garbage disposal? Sometimes food can get caught in the unit and cause the motor to overheat and then lock but before you call a plumber or replace your disposal try this quick maintenance tip.
First, make sure the disposal switch is off and look down the drain with a flashlight to see if there is a jam.
Carefully remove any items that should not be processed through the disposal. if you remove items and the disposal still hums when you try to turn it on go to Step 3.
With the unit still installed under the sink look at the bottom of the disposal, you will see a hole in the center as well as a red reset button. Insert a garbage disposal key or allen wrench into the hole and turn the key back and forth. This should loosen any blockage and free up the motor. Once this is accomplished, push the red reset button and you should be up and running again.