Sorry, but you almost certainly can't fix it. It is an awful product sold by 'Matsui'. They're not an Eastern company as you may have thought.
Take it back to the shop and demand a refund. I don't know how they can continue to sell these MP3 players!
Have a read of this:
http://forums.cnet.com/5208-4_102-0.html?forumID=71&threadID=218044&start=0
John, May 2007
