I reinstalled windows and some of my application requires d3dx9_xx.dll.
So I got it from dll-files.net
I also installed directx 9.
But some of my applications crashed like left 4 dead 2.
I launch the game and after choosing single player, it says left 4 dead 2 has stopped working.

It also happens to my Fallout 3.I play it and when I talk with people or go into other places.It will crash. Fallout 3 has stopped working.

Any solutions for this?
Oh and also Mafia 2 on my pc gets a black screen after the first screen