Disconnect the negative battery cable
I couldn't believe it worked. First the key fob wouldn't lock the doors, then the doors wouldn't lock, then the auto-lights wouldn't work, then the power windows stopped working, then the A/C blew hot air. What next!!?? I went to the mechanic and he spent 2 hours trying to figure out the issue, only to tell me we had major issues and this would cost a lot of money. Went to auto supply place to check the battery and alternator, they were just fine. Told them about this post and disconnecting the battery for a while, but they said it couldn't be that since the battery and alternator were working fine. I figured I had nothing to lose, so went home and disconnected the negative battery cable, left it like that for a while (about an hour), hooked it back up and VIOLA! Unbelievable, everything is working again. No issues. It is kind of like when your computer at home has issues, and nothing works, so you reboot it, and miraculously everything is fixed. Saved me hundreds of dollars!