Sansa 200 lists a full library of songs it does not actually contain

My device shows 291 songs in the library. All of the track info for each song is present: artist, song name etc. But the actually music is not on the disk. If i try to play a song it searches through the library seeking an actual music file but fails. When I connect the disk to a PC I cannot get any other programs to “see” this list. They all say the disc is empty. I have tried windows, my computer, sansa media and windows media player. According to them the disc is empty. So, in short, my device thinks it has a full library but these are just ghosts or figments of it’s imagination. None of the other programs see any evidence of these ghosts.

how can I wipe this erroneous info from my disk?