Have a 99 Plymouth Voyager

Have a 99 plymouth voyager. I was parked in the drive way with my van running and it just shut off out of no where. Now I have no power to anything, no wipers, no indicator lights, radio, windows etc. I replaced the battery and tested the starter to begin with. I tested all fuses and they are fine (under the hood and inside the vehicle). I hooked up an OBD2 but will read no codes. No one can figure out what the problem is. A few hours before this I did change 3 spark plugs but my van started just fine. No noises, no back fire or anything. It was running perfect. I would like to know what it could possibly be!