Electrical problem

I have a 95 toyota corolla with 86,000 miles on it, and a couple months ago I put in a radio, the next morning I drove to work and when I turned on my headlights and I heard a pop like a fuse and that day I checked the fuse and the problem is now I dont get power to the dashborad and instrument panel just power to the headlights. People tell me its a multifunction switch, how would I know what it is and to test to see if thats the problem