As I anticipated the diagnostic did not run. In all probability, the interface Electronics, - the SATA to USB bridge - inside the enclosure has failed. But there is no way of confirming this since that PCB is integrated with the HDD inside. Because of this we cannot try the HDD alone with a direct SATA connection, even if the HDD is good, which most probably is.

You may have to seek professional data recovery by WD authorised partners in your region. ( Replacing the board or separating the HDD for direct connection and trying is beyond the user)

https://support.wdc.com/Warranty/dat...y.aspx?lang=en