There is a fuseable link inline in the power supply wire. It sounds like it fried. This can happen easily if jumper cables are hooked up wrong, even for only a second. That's why the fusable link is there, to protect the other wiring. They also just can go bad for no apparent reason, though it's rare.
The fusable link is usually located under the hood, on the firewall, just above the distributor. It's inside a small piece of braided nylon covering.
Also, use a test light, and see just how good the ground point is on the alternator bracket where the ground wire from the batery attaches.
As Dino mentioned, grounds are very important, and are responsible for about 80% of all electrical troubles.