Can not format any flash drive or external hard drive, Can not delete any files from it. if you have this problem on your computer read this following post for a detailed resolution and solution to avoid it in future. http://bookingtohosting.blogspot.in/2014/07/remove-write-protection-on-usb-storage.html Reason: It may happen if a virus or any malicious software changes the registry and set up a policy on storage device in your computer.To remove this Policy and make your computer working smoothly again follow the steps below. 1. Open Start Menu 2. Run, type regedit and press Enter, this will open the registry editor. 3. Navigate to the following path: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\StorageDevicePolicies 4. Double click the key WriteProtect in the right pane and set the value to 0 In the Value Data Box and press OK button 5.Exit Registry.