If you moved it just cutting and pasting to your primary drive, try moving it back the same way.
Okay so I installed Steam, a gaming program, to my external hard drive, but I afterwards tried to move it to my computer and now the program is broken. It won't let me uninstall, and it won't let me download it again. What can I do? My computer is a Dell Inspiron, I just got it a few days ago. It runs Windows 7, has an Intel core i3. I don't know if any of that makes a difference or not.