What kind of lamp is in the luminaire? Was the original CB tripping? How did you test the cables for hotness?

Take down light fixture, and test white and black with multimeter set to volts AC. Should be 120. Fixture itself could be wired wrong, have a loose connection, or be shorting. I would guess loose connection since it intermittently worked and now it doesnt. If voltage is ok and connections are solid, then fixture is bad.

Another idea, you said three switches, is this a 4 way light? You may have wired incorrectly?

I'd be checking each connection in the circuit. It sounds like an intermittent connection in a wire nut or back-stab device.

All the lights are not working and there is voltage. You may be measuring induced voltage with an high impedance electronic multimeter. Try measuring with a low impedance device that has a (neon) lamp, or a solenoid tester (Jolt Bug).

On this circuit are 3 outlets , 3 outside lights (controlled by one switch), an interior light controlled by 1 switch, and an interior light controlled by 2 switches(3 way).

Thank you for your input.

Pat