Headlights, dome light, radio and horn inoperative

I have a 1989 Chevy Corsica, 74,000 miles on it with a 2.8l engine. Recently the headlights, dome light, radio and horn quit working and the seat belt warning light came on. I replaced the battery a month and a half ago and the alternator is two years old. Engine starts and runs and power windows, door locks, wipers, back-up lights, blinkers, stop lights
and air conditioner work fine. I would appreciate any help that you can give me. Thanks in advance.