Check the battery first -- chances are, it's electrical. Also, make sure you're fueled -- your fuel gauge could be broken, too! Do see a qualified mechanic ASAP.
The first thing i would do is to double check and make sure the connection to your battery is securly fastened. Next i would have my alternator checked to make sure it is functioning properly. If both of those check out then i would go to spark plugs, plug wires etc.
