weird electrical problem please help

i bought a '95 stang a few monthes ago and my dash lights, ashtray light and horn didn't work right. i installed new fog lamps, they worked fine for a week and after that they went out(bulb's ok) and the instrument panel illumination and the horn didn't work at all. above that, when the front lights were turned on i couldn't start the car and i must turn the light switch in and out a few times so that the lights will turn off and i could start the car. and the front lights are working only when i have the foglamp switch on. i took out the fog lights but still the same problem: front lights don't turn off if the fog lamp switch isn't turned on, the dash lights and the horn don't work either way
i found two wires(green and black) going from under the dash under the hood(in the uper left corner) and they have a melted litlle black plastic case(doesn't look like a relay and other 2 wires should go out from it i think). i dont know what it is and where it was going to
i have the haynes manual but i couldnt manage to work it out
if you understand my problem please guys i need some help