The solution is as follows:
1, the reason for the U disk itself: if there is a small switch on the U disk write protection, it only needs to be dialed.
2. If not, get some tools.
3, take the U disk apart, find the copper sheet, which should have a copper sheet is sunk, only to pick up, and the above copper sheet all contact on the line.
4, if it is a memory card, there is generally a card reader, and there is a small switch on the card reader, dial him down.
5, not the reason of the U disk itself: you need to kill the U disk virus, but not the use of the system's own formatting. If you still can't, use ChipGenus to test the USB flash drive chip model, then download the corresponding USB flash drive chip model mass production tool and the tutorial on the tool that should be mass produced, and re-mass format the USB flash drive.