You should get it fixed by iBasso, they do it for free during the one year warranty as long as you pay for shipping it to them, they'll ship it free to you. As far as it dying, if it is just a mechanical issue (contacts are bad due to plug insertions), you can buy those plugs on the web, mouser and digikey should have the connector available. You'll need to do some soldering to the board. if you have enough courage, you'll need to open up the player and check the connector shape, then go to one of those sites and type 3.5 mm female plug.
Is the warranty still valid if I bought it 2nd hand?