if you've just been using the car charger try using a wall charger, mine done the same on a trip and i bought a new car charger first, no help, then in the shop before i bought a battery got the guy to try a wallcharger out and afer a few trys it would charge again.

dont know about american markets, but it uses the same battery as the 5800 which was reasonably popular here so most small phone stores stock them if its totally dead.