Hi Twiggy. Unfortunately it sounds like your player has been hacked. Many players off of eBay have been hacked to read more memory that there really is. Follow the instructions posted here:
How To: Removing a Memory Hack
If it is hacked. Contact the seller immediately. Chances are good that he knows this and will try to blame it on you for formatting your player. Formatting your player does NOT mess it up. The ONLY reason sellers say that is because they don't want buyers to discover the hack. If the seller offers to give you a refund if you ship the player back to him, don't do it. Chances are you will never see your money or another player again. Open a dispute through Paypal stating the item is not as described.
Guess you can tell I've been through this before. Hope my advice helps.