Flip the switch on your breaker box that powers the garbage disposal in order to completely turn off any power going to the appliance.
Shine a light down the sink drain to see if there are any visible items stuck in the disposal.
Use tongs or pliers to remove items that are obviously blocking the disposal. Never stick your hand into the disposal.
Look underneath the garbage disposal (under your sink) and locate the hole in the center that's shaped like a hexagon (with six sides).
Insert a hexagonal wrench into the hole and turn it one whole revolution in both clockwise and counterclockwise directions.
Flip the breaker switch, turn on the faucet and turn on the disposal to see if it's working as it should.