Have a 91 honda accord....it will not start...at one time someone told me to tap on the starter it started....now it will not....i had the battery ck that was ok...could it be my alternator?

If, when the switch is turned, the starter motor does not operate at all but the solenoid clicks, the problem lies with either the battery, the main solenoid contacts, or the starter motor. If, as you say, the battery is good, and fully charged, that would mean that is was either the solenoid contacts or the starter motor.
If the solenoid plunger cannot be heard (no click), the battery is bad, the fusible link is burned, or the solenoid itself is defective. Once again, if the battery is good, it would be the fusible link, or the solenoid. The fusible link is in the engine compartment fuse block (the box on the upper left as you face the vehicle). It is either 80A or 100A.
If you want to test the circuit, you can run a fairly heavy INSULATED wire between your pos. battery post and the SMALL terminal on the solenoid (just touch the end to the solenoid). If the starter turns, you may have a ignition switch, neutral start switch, or some other wiring problem.
Your alternator is not the problem.
Hope this is helpful.