Plug the disposal and fill up the sink with hot water and detergent. Unplug and run the disposal. The spinning disk forces the water down the drain like a pump. This should clear the disposal and the drain line. If not, you'll need to inspect the plumbing. Old pipes made of iron clog easily due to internal corrosion and should be replaced with copper.
Physically remove lodged objects. If a large object has become lodged in your garbage disposal, you will need to remove it before proceeding with the cleaning process. First, it is important that you turn off the fuse that supplies power to the disposal unit. This is to ensure that it does not turn on during cleaning. Alternatively, you may be able to unplug it from under the sink, depending on the design.
The metal sink flange that sits directly inside the sink drain is typically sealed around the top with plumber’s putty (a clay-like sealant) and then secured from under the sink with bolts. If the plumber’s putty deteriorates, or the bolts loosen, the flange can no longer form a watertight seal between the sink drain and the disposal—which could cause a leak at the top of the unit.
If water is leaking from the disposal it more than likely needs a seal replaced but also could be a more serious problem. A leak can occur at the rings that are installed around the sink’s drain hole, called the sink flange. In that case, it can either be that the rings need to be tightened or that the plumber’s putty is faulty and needs to be reapplied correctly.
If the garbage disposal won't turn on but the motor makes a humming sound when you flip the switch, it indicates that the inner flywheel is jammed. Usually, this causes the appliance's reset button to pop or the circuit breaker to trip very quickly. This is not a situation you want to continue for very long, as it can burn out the disposer's motor unless the reset button or circuit breaker shuts things off.
If your garbage disposal is making a clicking or rattling sound, there may be some food particles that will not grind up inside. Remove power from disposer, reach into the sink hole with a pair of tongs and remove anything that is still down in the disposer. Test your disposer to be sure the noise is gone. If not continue troubleshooting your disposer issue (see below).