If you hear a humming noise, something might be jammed in the disposal. You can use an allen wrench made for disposals (if applicable) to move the internal mechanism back and forth. This will free most objects lodged inside. After freeing the object make sure you remove it.

No Sound

When there is no sound, try pressing the reset button (if applicable). Another suggestion is to run an extension cord from a known good electrical outlet to the disposal to make sure there is not an electrical problem.

Removing Objects

When you need to remove objects from a disposal, a small shop vacuum can be used or tongs work also.

Disclaimer: For safety, check and obey all national and local electrical laws and permits.