Cant find drive in my computer

I was upgrading my computer and i saved all my documents to my hard drive and i deleted all the partitions even the one to the simpletech now when i plug it in it dosent say anything and the drive is not under My Computer but my other drives are listed Hi! I think I might have the same problem, I have a WD mybook studio edition 1TB (I think) and it doesent connect to the computer. I cant see it in "my computer" but in device manager it is listed as "disk drive".
Some one know what the problem might be? please help!

PS. I just realized that i might have had the external harddrive connected while I was formatting my laptop. I heard from a friend that this might cause some troubble but if I am lucky I would be able to retrieve the information anyways.