Get a test light or voltmeter and follow the power path till you find where it is lost. Ensure you have clean battery terminals and wire ends. Sometimes, merely removing and cleaning the battery connections is all that is needed. Check the ground wire from the battery to ensure that there is a good clean connection the the vehicle. If you have jumpered it and inadvertently reversed the polarity, even momentarily, you may have blew the main fuse or burned up the fusable link, whichever it has.
