My 1990 acura legend won't start or crank, but its not the starter that's wrong, what could be wrong??

some cars can lose the meshing of the starter drive to the teeth at the flywheel ringgear or flexplate if it is automatic. some honda type cars have the flexplate gear attached to the torque converter if it has an automatic. Bench test starter and evaluate, turn the engine and inspect the teeth of the driven gear

You can try starting after just turning the engine some with wrench. leave running and drive to get diagnosis.

this may seem obvious but did you check your battery and fuses? The starter requires a lot of power (amps) to crank the engine over. Check the battery with a voltmeter. If you are getting anything below 12.5V it could mean your battery is bad or your alternator isn't charging.