I replaced the drivers side headlight assembly and when I plugged it in, the horn went off but the lights did not come on
headlights on 1995 Acura Legend
I sounds like for some reason the alarm is going off. Retrace your steps and ensure all the electrical connectors are all correctly attached. Make sure a ground wire has not been left disconnected. I will look at one at work tomorrow and see if anything else comes to mind.