Hey there, manes!
I'm really sorry to hear about your WD My Passport's fatal error!
🙁 I'd recommend you to try using another computer and see if you'd be able to access your files from there. Another thing you should definitely try is uninstalling and re-installing the external HDD as a device from Device Manager.
https://technet.microsoft.com/en-us/library/cc725782.aspx
If you have a spare USB 3.0 cable, I'd give that one a try as well and see if the error will appear then.
As soon as you gain access to your data, make sure you copy it somewhere else, so you'd have a backup.
You mentioned that the test is not finding anything wrong with the WD My Passport, however, I'd strongly recommend you to run the Extended test as well and...