If you look on top off the starter you will see a single terminal connector with a black/red wire. Hook up a test light and see if there is power to this wire when you put the key in the START position. If you have power there and the engine does not crank, then you have a bad starter and it will need to be replaced.
If you do not have power there in the START position, then the problem could be in the ignition switch, clutch switch if it is a manual transmission or a bad Neutral Safety Switch (NSS) if it is an automatic transmission.
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. Good luck