Electrical Fault

[mr eitch]

After having recently had a stereo fitted by a friend, I have lost power to most of my electrics. The engine starts and stops but I have no dash lights, brake lights, headlights, windscreen wipers etc. My hazard lights still work though! Any ideas. I've checked the blade fuses in both fuse boxes and they all seem ok. There are some larger fuses, 30, 40, 100 amps but I'm not sure how to tell if they are blown. Any help would be much appreciated.

[jirehn]

Did you already check your alternator?