My cloud pr4100 hit by ransomeware

Its not quite clear what you are attempting to do. If you are attempting to access the My Cloud hard drive after connecting it to a Windows PC, you will need to use a Linux driver/emulator program since the My Cloud hard drives typically are formatted in a Linux format.

Linux File Systems for Windows by Paragon Software

There is more discussion at the following link on getting Windows to recognise a single bay/single drive My Cloud drive.