Missing Audio and Video

[Sweet Scars]

As suggested, a new thread for my problems. I hope you can help me.

Since I have cleaned my harddrive, some of my games aren't working really well anymore. I get black screens in Amnesia The Dark Descent and Justine. I can read the titles and hints, see option/loading screens, hear sounds and music, can even use the controls (the hand seems to appear close to doors, alas in the Justine game) but there is no video. Also the image behind the main title screen is gone.

In another thread I saw I had to reinstall Intel. I tried to figure this out, but it did not work out. I do not know a lot about computers, so I could possibly have gone wrong everywhere. According to my system I have an Intel Family. I have tried to replace it with some of the suggestions from the tutorial, but it did not work. I also couldn't update it. I think I have accidently deleted a system from my computer, which did cooperate with the Intel. I only have no clue what that system could have been and how I could to get it back..

It's not only in the Amnesia game that this is happening. The sound/audio in my Far Cry 3 game is gone as well. Both games are legal copies from the internet. It works out perfectly well in the loading screens, like in Amnesia, but as soon as the main title screen appears, the sound is gone. This also happens in the gameplay.
I think it's relevant to the same problem as my Amnesia game is having.

I'm sorry for the long post and my english. I hope you will be able to help me out anyway!