The battery issue is covered in the other post. As for the car mount, they have been a problem. Make sure it is not making contact with anything, as the contacts are the problem. if it will not work, get a replacement dock.
Replacement car docks are available - possibly free from TomTom. - check with them first. Third party vendors carry them also - Google it.
In windows explorer, if you see your device - can you explore it? If so, make a copy (with hidden files and folders set to show).
Did you leave it on the home dock for a few hours before you removed it? It was probably totally discharged when you brought it in, as your car mount would not have been charging it. If not - try that - you may not really need a battery yet.