poor battery connection or battery itself high resistance in battery cables would be some things to check plus beanch test starter itself
The starter has failed and needs replaced. Somthing inside the starter makes connection when you tap it.
Try tapping (not hitting) the starter cellinoid. Sounds like it might be time for a new one. Pick up a service manual at your local auto parts store.
Bad starter solenoid. Bad brushes more likely (worn out)
Does the engine crank over?
the solenoid is bad on the starter. soon after this problem starts tapping on the starter will not work either any further questions email me at crazyarmydad@hotmial.com
your starter is bad, just replace it.
You can turn the engine over by the bolt on the crank. But I do think it's the solenoid on the starter that's bad. try tapping the starter with a hammer while someone is trying to start it with the key. If it starts then you know you need a starter.
check the alternator
Did the starter make any noise previous to this? Try crossing the celenoid. Will it start right away if you get jumped by another vehicle? I know that NAPA will test starters for FREE all you have to do is take it out of the vehicle. Some stores can even check it on the vehicle. the electric fuel ignition may be malfunctioning
the solenoid on your starter is finished, replace the starter......
Possibly if the starter solenoid contacts are weakened as this will cause them to reconnect long enough to start the vehicle or the plunger is seized in the wrong position. Once you start tapping starters to engage them a replacement is on the horizon.
Batteries low. Starter's getting current but not enough.