Hi there, bjsm.
I'm really sorry that you're facing such a problem with your drive.
Unfortunately more often than not, whenever you take an external drive out of its enclosure it will probably ask you to reformat it or you won't be able to access its partition like in your case. So I'd recommend that you try to open it via Ubuntu Live USB/DVD (this is a freeware, bootable, portable version of Linux), to see if the partitions are properly recognized and accessible, so that you can get to your data.
Another option would be to try out data recovery software:
http://www.tomshardware.co.uk/forum/id-1644496/lost-data-recovery.html and http://pcsupport.about.com/od/filerecovery/tp/free-file-recovery-programs.htm.
And last but not least, you could go directly for a professional solution, such as a data recover company:
WD Data Recovery Partners.
Hopefully one of the first 2 options proves useful and you're able to recover your files. Please keep me updated.
Boogieman_WD