Check fuses first and foremost.

Using an ohm meter, check the resistance between the negative terminal on the battery and the engine block. You should get some number. If you get a infinate resistance, then your battery isn't grounding properly.

There must be a bad connection near the battery somewhere. I have a '76 sitting in my back yard that hasn't been started in almost a year and a half and the battery is still strong enough to light up the headlights, so if your battery was dead you would probably still be able to see something.

Good luck.
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If you listen to the radio in Portland, OR, you may know me as 'Portland's Favorite Soul Brother!'