The answer to 'how to fix garbage disposal' is to first unplug the disposal unit or turn off the circuit breaker to cut power. Then use an Allen wrench to manually turn the flywheel inside the disposal to clear any jams. Check for and remove any stuck objects, and reset the disposal by pressing the reset button. If the disposal still doesn't work, it may need to be replaced by a professional plumber.
Regular maintenance like running lemon or vinegar down the disposal can help prevent clogs and extend its lifespan. It's also important to avoid putting fibrous foods, grease, or other hard items down the disposal, as these can easily clog or damage the unit.