Hey there, 6on2!
I'm sorry to see you struggle with your WD My Passport Ultra!
🙁 Have you been using the external drive on Mac OS only or did you previously use it on Windows OS computers as well? I'd suggest you to check the Disk Utility on your Mac and give me more details about the WD My Passport's file system. I'd also suggest to click on Repair Disk and see if that will make the drive accessible again.
If you've got a Windows computer nearby, I'd also try plugging the drive there and see how it appears in the Windows' Disk Management. While at it, you can also try testing its health and SMART status using Data LifeGuard Diagnostics for Windows. Make sure you run the QUICK and EXTENDED test from the utility here:
http://products.wdc.com/support/kb.ashx?id=DGRqew
Hope this helps! Let me know how it goes though!
SuperSoph_WD