I just went through this same problem with my Kingston USB flash drive. I didn’t know why. After inserting it to my laptop, I received the “not formatted error” message. As I tried to format it after struggling for a long time, the windows popped out that “It is write protected…” What a ridiculous thing!
So, I tried every possible way to get back my inner data and save this flash drive. Firstly, remove the write protection: http://www.itrelated.info/remove-write-protection-from-... Secondly, recover the inner data at the aid of a USB drive recovery freeware: http://blog4mark.blogspot.com/2012/12/deleted-files-rec... Thirdly, format hid drive:
My computer=> right click your drive=> Format => Quick Format
It is just like a nightmare. But, fortunately, all of my data are recovered and the flash drive also returns to its normal use.
I hope my experience could help you.