fog lights dont work!!!help please

[Mac-man]

ok here is the deal..my foglights quit working after a buddy hooked up a stereo in my car. the fog light switch shows to be on but the light wont come on outside the car? could that be the relay.also i did the mustang world thing to make them come on using the convertible top method. couldit be a relay not working. the bulbs are new and test good, soi know it isnt them. all the wiring is together but i cant figure out what it is. also which relay would i check i dont have an owners manual so i dont know which relay is which. any help would be appreciated. my car looks like every other v6 right now and it is buggin the hell out of me