With my old Sansa E250r, I had a similar problem. New songs would not show up/play that are on the card (They would show up when I put the card in my phone and worked there) so it would be something with the player. Not sure what.
That mp3 player also would be “filled” even after reformatting it but then say there were no songs on it and wouldnt let me add any either. Not sure if the same is happening to yours.
