Hey there, Murinzie.
Have you experienced any issues with the drive? Was there a single folder on that drive (which now is gone)? I'd recommend that you check if it hasn't become hidden for some reason. In order to view hidden files and folders click on the start menu button and type "Folder Options", open it and click the "view" tab. Scroll a bit down and you should see "Hidden Files and Folders" with 2 options - select "Show hidden files, folders and drives" and click OK. After that check if you can see that folder.
If that doesn't seem to be the issue, I'd recommend that you go for data recovery software. You could check out the suggestions from these links:
http://www.tomshardware.co.uk/forum/id-1644496/lost-data-recovery.html & http://pcsupport.about.com/od/filerecovery/tp/free-file-recovery-programs.htm.
Please let me know how it goes.
Boogieman_WD