If the disposal jams/hums...
Turn the disposal off. After turning the disposal off, remove anything that has fallen into the grinding chamber. Insert an "unjamming" tool into the bottom and turn clockwise. Once the tool turns freely, remove whatever was causing the jam.
If the disposal is dead...
Press the red reset button located on the bottom of the disposal. If the disposal begins to hum and the reset trips again, it is still jammed. Repeat step #2 and #3.
Tech Tip - always use cold water when operating the disposal and run the water a few minutes before and after as well as during use. The disposal works by grinding the garbage into a "puree" and water acts as a lubricant to move the matter through the pipes. Letting the water run before use will coat the pipes. Running water during the disposal process helps liquefy the garbage, and keeping the tap flowing afterward helps "wash down". Food particles, which remain in your disposal, can cause odors. Put a combination of ice cubes and lemon peel in the disposal, run it for about thirty seconds, and then run cold water through the disposal. Disposal cleaner or degreaser may help too. Because a garbage disposal chops large amounts of waste an occasional clog is bound to occur. Don't use chemicals to break up a clog. If the solution doesn't work you will have a pipe filled with caustic chemicals. This could deteriorate the integrity of the pipe and make for a huge mess down the road.