IItronics MP3 not charging?

I have an iitronics mp3 player (imp-1805) which I charge through a usb connection to my PC. I tried to charge it today after charging a week or two ago and it is completely dead. Usually it just starts to charge no problem but not today.I only have it 3 years from new and its not a cheap one by any means. Has anyone any ideas? is the battery gone completely or is it something else? Im baffled.Thanks