MP3 is no longer recognized by my computer?

I have a Philips “Go Gear” MP3. I’ve had it for about a year, give or take. I have never had a problem with it, but about a week ago I plugged into the pc to add some songs and Windows Media wouldn’t recognize it. It charges by pc power and I have no problem charging it. It’s 8 GB and I still have plenty of room. Any clues as to why this happened are helpful! I’m fresh out of ideas. And yes I’ve been to the Philips website and their tools did nothing. I’m running Windows Vista and I’m pretty sure that has something to do with it! Just not sure what!