If you change drives, or even change folders on the existing drive, for that matter, you have to reinstall the software so that Windows can find it. You cannot simply copy a games folder from one drive, or folder, to another. Copying it from one place to another will create conflicting entries in the Windows Registry, and things just won't work any more.
You have to uninstall the game and re-install it to the new drive, or the new folder.
If you don't have the installation disk for the game or have some other inability to re-install it, then you'll have to put the old drive back in if you want to run the game.
P.S. It *is* possible to adjust Windows Registry settings so that they conform to the new drive's or folder's location, but that is such a pain and so risky that I wouldn't recommend it, unless you have someone to lead you through it.