I have a 1990 mazda protege. an just the other day out of the blue. all my lights an horn dont work. except my headlights, my blinkers, brake lights . running lights , hazards ,dashboard lights even the horn dont work. does anyone know what can be wrong, i checked the fuses an there all fine.

 

check grounds, you could had one come loose or is not making good contact anymore...then if, possible check relays...they sometimes control a lot more than we think..

 

I don't have a schematic here for this vehicle but IIRC the Tail Number Side light (TNS) relay will control all the functions you posted. Headlights are on a dedicated circuit.