Appliance Repair Questions? Ask a Technician for Answers ASAP
The motors in garbage disposals have a starting capacitor and/or starting windings to overcome the initial torque and limit the inrush current..
If you can turn the disposal freely, then the motor can't start because of the windings or the capacitor which have likely burned out.
Is the unit under warranty? If not them I fear that you will need to replace the disposal.