try to use Silicon power formatter
download it and follow this tips
http://www.flashdrive-repair.com/2013/06/download-silicon-power-formatter-v-37.html
or read this article
http://www.flashdrive-repair.com/2013/11/8-ways-to-fix-write-protected-usb-flash-drive-and-memory-card.html
Flash Drive Repair Software
December 2013