My Book became "read only"

Dear friends,
A new WD My Book 10T External HD, worked just fine for few weeks. Windows 7.
WD Discovery now showing it is “read only”.
Can’t move files into it, right clicking a file or folder in it (opening the context menu) will not show the options to Delete, Cut or Rename.
Pressing on delete key doesn’t work as well.
That same HD works fine on another computer.
No problems with other internal or external drives on that computer.

How to undo?
Thanks in advance

Did you set this 10TB external hard drive into read only mode in Diskpart by mistake? If so, you need to run remove readonly attribute command on the disk. Besides, this may also be caused by disk errors, which can be checked with CHKDSK.exe tool.

As far as I can understand a power shutdown made the disk become fault and act as if it was read only.
I had to format it.