If you unplug an USB disk while it’s in use, or I can image in thousands of other situations, it’s possible that the system recognizes that unit as read-only disk, and replug the disk or reboot the machine doesn’t solve the problem.
So here they are some commands to regain full access to the disk:
Open a DOS prompt and use diskpart command:
x:\>diskpart
DISKPART> list disk
Disk ### Status Size Free Dyn Gpt
——– ————- ——- ——- — —
Disk 0 Online 1862 GB 0 B
Disk 1 Online 465 GB 1024 KB
DISKPART> select disk n (where n is the readonly disk)
Disk n is now the selected disk.
DISKPART> ATTRIBUTES DISK CLEAR READONLY
A message will confirm the success of the operation.