When your garbage disposal is jammed, you can usually clear the jam by rotating the impeller back and forth. One well-known manufacturer includes a slot on the bottom of the unit so you can do this without reaching in through the top with a broom handle. This feature may be included on models from other manufacturers, and if so, it's easy to tell; just climb under the unit and look. If your garbage disposal has this slot, it fits a 1/4-inch Allen wrench, which may be found taped to the side of the disposal.
Clearing a Jam
Turn off the switch and the breaker in the main panel that controls the garbage disposal. If the breaker has tripped, be sure to push it all the way toward the outside of the panel until it clicks.
Rotate the impeller back and forth to free debris. If your unit has a slot for a wrenchette, crawl under the unit, insert the wrenchette in the slot and use it as a lever. If your unit has no slot for a wrenchette, insert a broom handle or wooden spoon through the top of the disposal and use it to turn the impeller.
Remove debris that comes loose, using a pair of tongs.
Turn the breaker back on when the impeller rotates freely, then push the red reset button on the unit. On some models this button is on the side of the canister, and on others, it's on the bottom. Make sure the button stays in -- if it doesn't, turn the breaker off and on again.
Turn on the water, then switch on the garbage disposal. Repeat the procedure for clearing the jam if it hums but doesn't spin.