Verified answer

Be sure the switch is off and take a mop handle or bathroom plunger handle, stick it down the drain to the impeller that holds the blades. Use the stick to turn it counterclockwise (backward) a bit. Pull the stick out, turn on the water and hit the switch. Chances are there is a piece of bone or something else hard that keeps the motor from turning.

You also might want to use a flashlight to see if you can see anything stuck in there to jam it. I have used a long pair of tongs to pull things out of a disposal before.

Also check to see if it has an overload switch. Most disposals have a red button that pops out, kind of like a circuit breaker, usually on the bottom of the motor housing near where the wire enters. Push that back in to reset it.

The key is usually just an allen wrench. Check to see if key hole is plugged with rubber cap or grime.

Buy a new key, if you don't have an allen wrench that will fit it....They sell them at Wal-Mart or any other hardware store