Hi I have the same mower and it was working fine. Turn it off went in the house. When I came back out the tractor did not crank. It made a clicking noise at the solenoid. So I 1) serviced the battery in case I was out of juice. 2) I cleaned the posts with wire brush, 3) I banged softly on the starter in case it was stuck.

Still nothing. Any suggestions? Please help

Hi,
Do not suggest banging on the starter! It is likely either the switch not supply correct voltage/currect to the solenoid or the solenoid itself(most likely.) I have seen both fail at the same time, though rare. Both parts are mechanical in nature and are common failure points in the starting circuit.
Peace,
Clarke

Thanks Clarke.

It could be a loose ground wire a bad starter or a bad battery