Cannot mount on Mac

"I think you’ll need to use a more advanced disk repair app like Drive Genius or your other option is to ship the drive out to a data recovery service like Drive Savers

Hopefully you didn’t use the built-in 256-bit AES Encryption with WD Security software as then you would have no means to recover unless Western Digital has a recovery option which you’ll need to talk with them. WD may also offer a recovery service if the drive is still under warranty so it maybe worth your effort to check that direction first.

Update (09/30/2018)

I’m happy you were able to recovery your files!

I’m not sure I follow your direction here…

The first question: do you have your AirPort on a Surge suppressor or better yet a UPS. The issue is if the AirPort lost power (and via the USB connection the drive as well) so the wink out of power was the cause.

The second question: If this is your backup solution then I would recommend a better drive system. I don’t like one drive solutions as they put your data a risk. I use a RAID 5 solution

If you want to try to salvage your drive I would recommend you do a complete wipe and restore your data. I would still be cautious on depending on it."