Car won't start

I have a 1999 Beetle. It sat for a few months and wwhen I tried to start it it was dead. I recharged the battery and it started. I brought it to be detailed and when I went to pick it up a few days later, it won't start. Nothing works AT ALL (no radio, no lights) when I turn the key it does nothing!! Any Advice??!!

It sounds like the battery is dead.