Why won’t car start?

You may have a couple of problems here. Check for power at the starter solenoid wire when in the crank position, it should have battery voltage on that wire, if it doesn't then it could be an ignition switch or safety switch, or even broken wiring. If you have steady power and the starter doesn't spin then you most likely have a bad starter. On some of these the solenoid's contacts were replaceable but you won't know that until you remove the starter and inspect it.