Encrypted HDD does not appear in Disk Utility or Finder or Terminal

I recently reformatted a 320 GB external HDD as Encyrpted, Journaled HFS+ using Mountain Lion. For several weeks, it worked flawlessly. I was able to back up financial documents with the security of disk-level encryption. When connected, the drive would mount and prompt for password (as expected).

Then one day I knocked against my desk while the drive was connected, pulling the FireWire cable out of the external HDD. It lost power and disconnected, causing the error message about disconnecting disks before ejecting them.

I immediately plugged it in and attempted to find it. Unfortunately, it didn't appear in Finder. It didn't appear in Disk Utility. It didn't appear in /Volumes or on diskutil list. I haven't been able to get it since then.

I have:

A) Restarted with HDD attached

B) Restarted without HDD attached

C) Connected with a different FireWire cable, then tried connecting with a USB cable

C) Run "Repair Disk" on my main internal HD while in Recovery Mode, without and then with HDD attached

D) Tried connecting to other Macs, using combinations of Lion and Mountain Lion, FireWire and USB

Does anyone have any additional tricks to try? The data is backed up, so it's ok if I lose it. But I would love to unbrick this drive that I purchased before considering it useless.