Please Help - Brake lights out on 2000 Jeep Grand Cherokee?

It started with my driver side brake light not working. It seemed that I could have either signal or brake, but not both. I tried turning the plug a bit and now none of the brake lights work including top 3rd one. tail lights work, when head lights are on or not, but left signal still wont work, and all brakes are dead. I read about switch by pedal, is there a fuse for this? Also, others talked about ground, where do I look for that? I haven't touched any wires, just replaced that bulb in the back, which is fine. Could it be the contacts inside the brake unit? with the contacts from from the plug? Thank you SO MUCH for your help with this.