are you able to format the player while in msc mode?
right-click on it while in my computer and select the format option, make sure your selecting your mp3 as this will delete all the files off the device. It if says failed to format, try doing it thorugh disk management. To get there you can right-click on my computer and select manage from the drop down menu. From here you will see disk management on the left hand side. Then a larger rectangular box with the drive letter that represents your player, you can right click on this and select format.
Or just try a different computer, if its the same everywhere then youll probably have to end up emailing sandisk, stating everything you tried. They will probably ask you to do a couple more things, but if you keep at it, youll end up with an RMA*.
*RMA = Return Merchandice Authorization
