No brake lights or turn signals on 1999 Chevy Lumina

This is a common problem. If your 3rd brake lite works, then the problem is the turn signal switch. This componet is in the steering column. THere are a couple of variations depending on whether or not you have radio controls on the steering wheel. Either way, its a pretty detailed job requiring a pretty high level of experience and tools available. You will have to pull the steering wheel and airbag make the repair and put it all back together. If the 3rd brake lite doesn't work either, then it could be a whole different senerio.