I'd start by throwing the breaker to deenergize the circuit. Then check all connections under the wire nuts since you might have a loose connection somewhere on the circuit. If that is ok, the reenergize the circuit and use a voltage tester to start testing and see if you can isolate the problem. I would further check all the insulation on the light wires as the heat of the lights could have made it go bad. Using hotter than rated bulbs can burn the insulation causing a short. In 1985 they went from a 75 degree centigrade type nm sheathed electrical cable to a 90 degree centigrade type nm-b sheathed electrical cable to handle the heat better. Which is why new light fixtures contain a warning that it may not be compatible with the older wire.
Post back with the results. The fan working and the light not working points me to the fan/light combo and the junction box above it.