Lift the plunger and check if the water starts flowing.
Then, pour one-fourth cup of baking soda and a cup of white vinegar into the garbage disposal unit. Having a bit of fizz and foam is normal and nothing to worry about. Make sure that the garbage disposal unit is still turned OFF during this step.

The combination of baking soda and vinegar creates a mixture that helps clean and unclog your drain pipes but in a much gentler and safer way compared to your typical drain cleaner and this is one of the best methods in unclogging when garbage your disposal is not draining water.
Wait about five to ten minutes for the baking soda and white vinegar combination to do their job. Then, pour in some warm down the drain water to flush out the cleaning agent.

When water drains completely, you can turn your disposal unit back to ON, and you’re done. If your garbage disposal unit still doesn’t work, it would depend on you if you want to detach the garbage disposal from the sink and check the unit thoroughly and also peek inside the drainpipe with a flashlight. But if you don’t want to be hassled, you might want to call for a plumber’s service.