When glass or other debris falls into the garbage disposal, you can hear it banging around inside. The debris may become lodged in the teeth of the disposal, in which case the disposal will not work, even though you can hear a low electric hum.
The first thing you need to do is to turn off your disposal. Flip off the switch in the kitchen and flip off the fuse box switch that feeds the electrical current going to your disposal. Test that you have shut power off at the fuse box by flipping the kitchen disposal switch on again to make sure you have killed the power completely.
Every garbage disposal has a "hole" in the bottom where you can insert a ¼ inch hex wrench. With the power off, use the hex wrench to spin the disposal backward and forward, loosening the debris. Turn the power on at the fuse box and again at the kitchen switch and run water into the disposal to see if the debris will go down the drain.
If this does not work, you will need to remove the disposal completely. It is easier than you think and only requires one Phillips-head and one flat-head screwdriver. With the power off, use the flat-head screwdriver to loosen the disposal drain hose from your drainpipe. Use the Phillips-head screwdriver to loosen the screws around the neck of the disposal, and use the Phillips-head to rotate the mounting ring counterclockwise. Turn the disposal upside down so that the debris falls out.
Many foods will clog your disposal by building up grime along the walls and drain of your disposal. Or perhaps you have simply put too much food down the disposal at one time and it has become clogged at the drain point.
With your disposal running, run plenty of water into the disposal and see if that will remove the clog. If not, kill all power to your disposal by turning off the power at the fuse box as well as the kitchen switch.
With the power off, use the flat-head screwdriver to loosen the disposal drain hose from your drainpipe. Use the Phillips-head screwdriver to loosen the screws around the neck of your disposal, and use the Phillips head to rotate the mounting ring counterclockwise. Then clear the obstructions from the disposal exit hole as well as the drainpipe.
Reattach your disposal, return power to it and run the disposal with plenty of water flowing into it to clear any remaining food.