Downloading after reformatting.

Well, as i said in a previous topic, i reformated my PC and i wanted to know how to reinstalled it the game.

Now here goes the problem, the reformat wasn't total, some important documents were saved, and there were still some pieces of Demigod on the Registry. When i finished downloading Demigod, guess what, "invalid download". I tried deleting every piece of registry of the game, but it says is not possible, so I can't delete everything, what should I do?