Do not attempt to use your PC to format the player !! The player uses a hidden partition that contains the OS. There is no consumer access or repair for this partition.
There exists a common misunderstanding about the type of micro USB cables that work with SanDisk players. A working cable must support data transfer (syncing) AND battery charging… Most micro USB cables ($ Store, $5 Store, etc) only support battery charging; not data transfer. New Clip Sport and Clip Jam players come with a short cable (about 9 inches) for both functions.
If you could get the player recognized by your PC, many helpful posts in this Forum suggest applying the most recent Firmware file into the root directory of the player. (See tbis link.)
