I havn't been able to find the solution to this anywhere.

When I open my game 3/4 of the screen is black and the other 1/4 on the top right is white. There is nothing I can click to fix it. I have uninstalled and checked for missing files but nothing happens. This game used to work for me then it somehow broke with missing textures and then stopped working all together.

http://support.facepunchstudios.com/kb/articles/6-i-get-crashes-on-start-or-the-screen-is-just-black

This might be of help, not sure.