wwb

If it doesn't crank, it darn sure ain't gonna start.

Possibilities.....

The "start" position on the ignition switch is bad - check for voltage at solenoid connection with switch turned to "start"

Bad solenoid... if you have voltage at the connection but do not hear the solenoid pull in, it's bad

Bad starter motor.... in the solenoid gives a good "clunk" but the motor doesn't crank, it's probably the motor.... brushes, commutator, or armature windings..... could also be that the contracts in the solenoid are bad.

Battery just doesn't have the poop to crank the engine.... if the solenoid pulls in and then drops back out when the current draw from trying to crank drops the batttery voltage, you may need a battery. Try jumping it from a healthy vehicle?