L4D2 Black screen but still hearing sounds HELP!

[Tribemember 123]

i recently bought L4D2 but it keeps going into a black screen when i load it up i have tried to redownload it but it says 11062 files are missing and i dont know what to do i will be willing to give u a free Dota 2 if u help me out. I have also tried putting in the launch options -autoconfig but that didnt work so please i ask for your help. If you can help me pls post below a step by step conclusion, Thanks

[R∃M1X]

someone said to go to properties on the launcher and tick "640x480" box but i cant find it.

[Bullet]

r click icon then properties

[Chet]

Im having the same problems. :/

[Ocin.]

Go to Steam -> Library -> rightclick Left4Dead2 -> Properties -> Launch options -> type in ''-w 1680 -refresh 60''. ''-w 1680'' sets the resolution, so change the value to your monitor's one (e.g. Monitor resolution = 1920 x 1200 [type in ''-w 1920''] . ''-refresh 60'' will set the Hz, the refresh rate, of your monitor to 60Hz (60 works for me).