LEFT 4 DEAD 2 WILL NOT LAUNCH

[Seventy-Three]

Hi.

So I have windows 7. (idk if thats important) Anyway so today i bought l4d2. I installled it regularly. then i tried to launch it and i got this error:

Failed to start game (unknown error).

See the Steam support site for more information

I deleted and reinstalled the game and the same thing happened. I deleted my appcache folder and restarted my computer and the same thing happened. what should i do?

[Marble]

What's the rest of your system specs and are you using the latest drivers and DirectX version?

[Pewpewmoar]

Try exiting steam (not minimizing, exiting from the menu), and restarting in Administrator mode. You can do this by right clicking your steam shortcut, and selecting 'Run as Administrator'.

Beyond that, there's this suggestion:

Originally posted by CareTaker:

I had this same problem with a fresh install of Steam and L4D2 on a secondary internal hard drive. I found my problem was a permissions issue with one or more folder in my %userprofile% directory (typically c:\users\[username]).

In my case I had to take ownership of ALL the files contained in my user profile directory, then reset all the permissions to inherit from parent.

To take ownership, go to Start -> Run -> "%userprofile%\appdata"
Then for each of the folders, follow these directions (be sure to select the "replace owner on subcontainers" option:
http://technet.microsoft.com/en-us/library/cc753659.aspx

Then I had to reset the permissions of all the child objects. I did this by doing the following for each folder:
Right click -> Properties -> Security tab -> Advanced -> Change Permissions... -> check "Replace all child object permissions..." -> OK

Hopefully this will help!

from THIS discussion.