Q: When I put the key in the ignition, all lights come on but it will not start.

There should be power available at the starter solenoid and it is grounded by it’s mounting to the engine and there is a ground cable attached to one of the mounting bolts. When the key is turned, there should be a signal at the starter that switches the solenoid and supplies power to the starter assembly. If this signal is present while trying to start the vehicle and nothing happens, the starter is faulty. If there is no signal, there is a problem on the ignition side of the circuit whether is is a relay, a switch or in the wiring. Consider hiring an experienced technician like one from YourMechanic who can come out to the vehicle and run a few tests to offer a more personal diagnosis of your no start concerns.