If a garbage disposal hums when it should be grinding or draining it is jammed.
If you hear your garbage disposal humming, you should shut it down immediately. If it continues to run it in this condition, the motor will burn and cause more damage.
To check what is happening, first disconnect the power to the disposal.
Under the sink you’ll find a hex shaped hole and a wrench (that is also hex shaped). The wrench fits into the hex shaped hole. With the wrench try to move it so that the jam is released.
If this is not successful, you need to call a professional plumber.
If the disposal is humming and not draining, this is a plumbing problem and won’t be fixed by a simple turn of the hex-shaped wrench. A plumber is definitely needed to handle the problem.