Nostalrius Begins - Quality wow vanilla realm (1.12)

In preparation for Elysiums launch I preemptively installed Vanilla WoW, everything was working fine until today. When I launch it I get this error message "World of Warcraft was unable to start up 3D acceleration. Please make sure Directx 9.0c is installed and your video drivers are up-to-date." I went and tried downloading DX9 and when I clicked install it said I must own an older version of Windows to even install it. I don't understand why this happened out of no where when it was working perfectly fine not long ago.

Some other program has either changed your DirectX 9.0c files or is hogging the required driver. Try this download link to reinstall it: https://www.microsoft.com/en-gb/download/details.aspx?id=34429