You say that the disposal only rotates when the dishwasher is running? Are you saying if you turn the disposal on it will not work unless the dishwasher is also on and then it rotates? If you have an on/off switch for the disposal it should at least try to turn when you turn it on. On the bottom of the disposal is a red reset button. If the disposal will not come on push that reset button to reset the breaker. This may solve your problem once you get the disposal running and clean it out. If it trips again something is lodged in the unit and you must clear it out. Turn the power off at the service panel before attempting this. It may also be getting power from a GFCI receptacle. Check the ones in the kitchen to see if they have tripped. Reset them by pushing the red button, and see if that fixes the problem. The drain line from the disposal may also be clogged. Get a bucket and remove the drain line from the disposal and check for a clog in the line and inside the disposal. If you find none then move to the trap under the sink. You may find one of these clogged. Use ice to sharpen the disposal blades and keep the unit fresh at least once every 3 months. Just put ice cubes in the unit and turn it on for about 15 seconds.