Kimie, I'm sorry you are having this problem with your treadmill. When the treadmill motor doesn't start it can be caused by the motor, controller, console, or a wiring harness. Disconnect power from the unit and remove the key. Check the wire harness connections from the console to the controller and from the controller to the motor. If the connections and wires appear ok, reconnect the power and insert the key again. If it still won't start, I recommend having a technician make this check and repair. You can call 1-800-469-4663 to schedule a tech to come out.