A common cause of why your USB flash drive cannot be used as usual, meaning files cannot be added or deleted from it, is that it's write-protected. USB drives can get into this state not just as a result of a direct human action, but also because of a manufacturer setting or due to a disk error. If you ruled out all the other causes that might have led your USB drive to malfunction (malware infections, other disk errors, no more free disk space on it, files set to read-only, etc.), then here are the most common 4 methods of removing the write protection from a USB drive.
1. Check for physical locks
As obvious as it may seem, many people simply forget that there are quite numerous models of USB storage drives that come with a physical lock switch that turns on write protection. You should check first if this switch isn't turned on, and turn it off.
2. Formatting the drive
If you don't care at all about the data existing on the USB drive and you just want to get rid of the write-protection and make the USB usable again, you can format it. Formatting the USB flash stick will remove its write protection, as well as all other files that were stored on this device, so make sure you use this option wisely. In order to format a USB stick, just plug it in to your computer's USB port and then, when detected and displayed by Windows as a drive in Windows Explorer, right-click it and select the "Format" option. Select the exFAT file system if the drive is larger than 32 GB, NTFS if the stick will be used only with Windows computer, and FAT32 if none of the two previous options apply, and press the "Format" (or "Start") button. Anyway, formatting the drive only to remove write-protection from it should be done only as a last resort method, when all other available ways lead to no success.
Choosing Formatting's Parameters
3. Using the command prompt and the diskpart utility
You should know that this method is not completely safe when it comes to your files, as it still may delete some files in the process, therefore trying to back up as much data as possible from the USB drive beforehand is highly recommended.
First, after you've plugged in the USB stick and backed up as much data as you could, launch the Command Prompt by typing "cmd" in Windows Search.
Next, when the Command Prompt window is opened, type diskpart and press Enter.
A new window will open. Type list disk in this newly-opened DiskPart window and press Enter. All the connected storage drives are displayed and you can identify the USB drive by its size.
The list disk command
Select the USB drive by typing select disk, followed by a space and the disk's number. To select Disk 1, for example, type select disk 1. Press Enter. If instead of disks, volumes are displayed, just use select volume plus the volume's number.
The select disk command
Type attributes disk clear readonly and press Enter. This should remove all write-protection file attributes from the disk. Finally, type Exit, press Enter, and check your USB disk. If the write-protection wasn't removed, you should also consider formatting the drive.
Clearing Disk's Write Protection
4. Editing the Windows Registry
Though editing the Windows Registry may seem scary to many users, this is actually the simplest, the most straightforward, and also my favorite method of getting rid of the write protection for a USB drive. Here's how it's done:
1. Open the Registry Editor, usually by typing regedit in the Windows Search;
2. Navigate to the following path, using the Registry Editor's left tree panel: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\StorageDevicePolicies
If once you reached the Control folder you notice that the StorageDevicePolicies directory is missing, there's no need to panic, you'll just have to create it yourself. Just right-click in the Control folder and select "New", then "Key." Name it StorageDevicePolicies and then open it. Next, right-click in the newly-created StorageDevicePolicies folder and select "New" then "DWORD (32-bit) value." Name this key WriteProtect and then save it. Double-click it to modify it, or right-click this newly-created key and choose "Modify.." from the context menu.
3. Double-click the WriteProtect entry or right-click it and choose "Modify..." from the context menu.
4. Set the Value Data parameter to 0 (zero) and press OK. Close the Registry Editor and restart your system.
Editing the Value Data
As you can see, removing the write protection from a USB drive can be done rather easily. Hopefully, you won't have to resort to formatting the drive in order to do it. Anyway, having to remove the write protection is still a better scenario than having to deal with a completely broken drive and needing to purchase a new one.