Can I re-install the game?

[TFEF]

No, you should be able to just uninstall and reinstall from the game's files. If you're on Windows, the folder the uninstall should be is C:/Program Files/Amnesia - The Dark Descent. For Steam, it is something like c:/program files/steam/steamapps/common/amnesia the dark descent. Just click uninstall and then reinstall the game using Steam.

Also, be cautious when messing about with integrated graphics cards. You can more or less damage your motherboard if you mess up, and you have to be really good at this type of thing to do it correctly.