That happened to me with one of my WD external drives (a 320GB too). I was using it as a backup to drives inside my desktop. A few days after I loaded everything up...poof, all gone. Luckily it was the backup and the originals were still in place.
Now I have a semi-fool proof system. I copy the contents of my recording to my main live show HD inside my desktop, and work on the files from there. All the while, I keep the original recordings on my JB3. After I finish editing the recording and track it out, I save it on the same drive, all tracked out, then I put the original file(s) on my external drive.
Finally, after I have copies on two different drives, I clear the files on my JB3.
I really should make extra sure I'm covered by making DVD-R backups of everything, but that is pretty time consuming. I'm hoping and praying that I can survive like this until BLU-Ray drives/media become a bit more affordable. Also, might want to note that I once thought that I could save space on my drives by not saving shows that I had uploaded to the archive. That was all fine and dandy until I looked up one of my shows on the archive and got some sort of page that said the files from that show were "missing." Luckily someone at the LMA must have found them because the show is back. Moral of the story is, don't trust the LMA as a backup.
I've also been thinking of getting an additional HD to back up my original files to keep offsite. God forbid if my house burns down (or someone steals my computer after my roomie leaves the front door open). And if it does burn down, it sure will be nice to have my recordings to listen to during the aftermath.
+T for your troubles. I hope someone else was recording some of those shows.
Just remember folks, Hard Drives make HORRIBLE backups. They are not very reliable. It is unlikely that 2 HD's might die at the same time, but not impossible. Also if you don't make frequent backups you may not notice that your backup HD is corrupted, then when your primary dies, you're screwed.
I find that all of this work is mandatory for me, as I don't listen to CD's much (especially not live shows), so I don't even have a backup of recent shows on CD. I usually playback at home from my desktop, and convert to MP3 to listen to in the car etc. on my iPod.