Ford Repair: 2000 explorer wont start, simple tests, multimeter

Question
I left the keys in the ignition overnight the car was turned off nut when I tried it the next day it wouldn't start it's not the battery I already tried that

Answer
Tom,

Have you tried completely disconnecting the battery and allow everything to reset? Otherwise you need to start with a good multimeter and check for battery power and ground going into the main power distribution box.  A fully charged battery should register 12.6 volts. Do a few of these simple tests and let me know what you find.