Before you call anyone, there are a couple of things worth trying — and one of them often does the job.
Try this first
If it hums but will not turn, the motor is fine and something is jammed. Switch off the power at the wall, use the small hex key that came with the unit to free the flywheel underneath, then press the reset button on the bottom. If it makes no sound at all, the reset button alone often fixes it.
If you are on septic, use it sparingly
This is the important one out here. A disposal sends a great deal of extra solid material into a septic tank, which fills it faster and makes the drain field work harder. Some septic systems cope; many would rather you scraped plates into the bin. If you are on a tank, it is worth knowing that before you use it heavily.
When it is genuinely finished
Water coming from the body of the unit rather than the connections means it has rusted through and cannot be repaired. Repeated tripping after a reset means the motor is going.
What it does not deal with
Cooking oil and fat. Those still go down warm and set further along the pipe, which is the usual reason a kitchen drain keeps blocking.