1995 jeep wrangler 4cyl not firing

Ok, this is what happened. My wife left the lights on and when she got out of school and tried to crank it but it would not start. So, this is where it gets bad she connects the jumper cables up backwards. When I checked the fuses the main 50 amp fuse that controls the fuse box was blown. I checked the rest of the fuses and they were ok. Any thing that I am missing? Please help me out TIA.