The Samsung YP-910 is an MP3 player tied directly to the Napster music download service, but that's about all I know about it. So it's time for some quick research.

First stop, Samsung corporate. A few failed searches later, I find that if I search for the exact model "YP-910" in the Support area, I can find the user's guide in PDF format.

Reading through that, there's no mention of any sort of USB charging capability, so my suspicion is that you've never been able to charge through the USB cord and you were just confusing the YP-910 with a cellphone or similar that can often charge through a USB wire.

More importantly, the User's Guide indicates everything that's included with this product:

What we want here is the product number of the charger unit, because I think you just need to get a new one. The part you seek is a Samsung AH44-00036B.

Now just use Google to search for that specific product: Google search for Samsung AH44-00036B. Right at the top:

There ya go: the first match has a new charger for $39. Not too bad:

Click on the graphic above and you can buy a replacement charger. I think that's your best bet for getting your Samsung MP3 player working again.

Good luck!