1st make sure connections on solenoid are secure and no broken connections. Next While someone simultaneously trys to start, tap gently with a small rubber hammer on solenoid . If it cranks over solenoid is bad. Next make sure cable from positive side of battery to solenoid isnt broken or disconnected. Next make sure starter gear is not stuck in flywheel. With sparkplug wire disconnected and positive battery cable also disconnected. Try to turn flywheel manually clockwise with both hands. If stuck rock flywheel back n forth to free. ( make sure deck is up, pto off, trans is in neutral) if this freed up flywheel starter gear is worn and needs replacing. Lastly are you trying to crank over with choke already engaged if so disengage and try again. With choke on motor is harder to turn over.