Problem with sansa clip+ firmware

Try holding the REW (<<) button while plugging the player into the computer. It should be recognized and you’ll be able to format it, fixing the corrupted FAT issue. Note this will remove all user-added content AND Rockbox (but not its boot-loader from the firmware) so you’ll have to re-load everything (including Rockbox). As the FORMAT will not remove the boot-loader from the firmware, I would suggest re-applying the latest Sansa firmware at the same time, which will over-write the Rockbox boot-loader and then starting over from scratch.