Dead battery

Makle sure battery has a full charge, if it is down very far, don't let the alternator charge it. Take it off and get it charged. You should also check your charging system. If there is excessive battery drain with everything off, check how much drain there is? If excessive, check for a lite left on somewhere, interior--under the hood, anywhere. Best time to check is in the dark. If there is a problem on a fused circuit, pull and replace fuses one at a time. When you pull the fuse on a faulty circuit, the excess drain goes away.