World of Warcraft was unable to start up 3D acceleration.

[Varyation]

I was playing nostalrius a few hours ago and it was fine but when i tried to go back on it and now it wont start and a window pops up saying " World of Warcraft was unable to start up 3D acceleration " I've tried installing new drivers and directx but its not fixing it, i also reinstalled the game. help pls