[FredM]

You will probably find the solenoid is kaput!!, most likely a pull in wire has parted and the solenoid has gone open circuit, have you bridged across the battery cable pole to the starter motor pole, this will show if the starter is kaput, make sure the tractor is in neutral before trying, I have to mention that and you will know because you are testing the starter.

Bridge from the red cable to the opposite pole and the starter should spin, let us know how that goes.

 

[FredM]

What does checked mean?

To find out if the starter motor is ok, bridge across with the screw driver as I suggested and you will find out if the motor is ok.

Could be the starter drive/pinion gear is jammed in the ring gear and cannot be turned.

He will find out if it is jammed after he does the above BigT.