[Chemist31]

This is a little different question than I have seen searching the various forums.
I had two WD 500GB external hard drives connected (via USB) and working well (not a trusting soul). Due to the dearth of USB ports on this old computer (which still works well), I have to disconnect one of these hard drives to upload photos etc. I use the safe hardware disconnect to do this and then plug the 2nd hard drive back in. It works fine until now. Evidently the 2nd hard drive was not "stopped" the last time I disconnected it and now I cannot get it to be recognized. I have tried all of the WD suggestions but none work. I did get it listed under "my computer once" but when I tried to open it I got the message to stop it (which I did). Shutting down the computer and then powering up the hard drive (it does spin up) and plugging it in does not work. Sorry about the long description but and help will be appreciated.
Thanks much!