Could be a blown "short stop" circuit breaker. Some will auto reset when the battery is disconnected and reconnected, some have a manual reset button, and some do not have a reset function and need replacement. They are sold at most auto parts stores.
Look for something
like this, inline on the hot wire between the battery and slide. They come in various amperage ratings. If you have no voltage between the two posts, the breaker is either bad, or needs resetting. If you are replacing one, replace with same amperage rating, as that of the old unit.
