Major Electrical Issues

I need help figuring out whats wrong with my Jeep. Its a 95 ZJ 4.0l 4x2 Auto Limited. I have been having issues with my CEL coming on and giving me codes for voltage too high and too low. When the light comes on the gauge will fluctuate between 1/4 and full over charge. Recently I went out and started the truck, all was well. Came out to leave and the found that most of the electrical components didn't work. I only have dash lights, headlights,  running lights, front wipers, and the instrument cluster does work. I have no heat/ac, no VIC, no radio, no interior lights, no turn signals, no flashers, no brake lights, and no rear wiper. I have no idea where to start in diagnosing this. Jeep isn't legally driveable at the moment and I need it to be.