Do a right-click on the DoD:S game and go to the properties. Look for Verify Integrity of Game Cache under Local Files. It should scan the game and make sure everything is there, and if not it will get what it needs from Steam. That's what I do when CS:S or CS:GO is messed up unless someone else has encountered a similar problem and knows a better fix.
Did any of the methods mentioned work out?

alright i`ll trry that as well
Completely exit Steam
Right-click on the shortcut which you use to launch Steam
Select "Run as Administrator"
Launch Steam again and try verifying game files
Note: Do not run the verification process while performing other system-intensive processes, such as defragmenting your hard drive or scanning for viruses.
Do not run this process for multiple games at the same time.
Exit Steam.
Click Start > Run
Type the following command:
"C:\Program Files (x86)\Steam\bin\SteamService.exe" /repair
(If you have installed Steam to another path, please replace C:\Program Files (x86)\Steam with the correct path.)
This command requires administrator privileges and may take a few minutes.
Launch Steam and test the issue again.
Exit Steam and go to the folder called C:\Program Files\Steam\ (this is the default location for a Steam installation - if you set a different installation directory, you will need to browse to it).
Delete all of the files in this folder except for the following (If you want to, you can delete the files not mentioned below but not permanently delete them in your trash/recycle bin application just in case):
- \Steamapps\ and \Userdata\ folders
- Steam.exe (this file is listed as an application and features the black and white Steam logo)
Restart your computer.
Then, you will need to launch Steam.exe from within the Steam installation folder, and not from a pre-existing shortcut.
With Steam running, re-test the original issue.
Note: This process will not affect your currently installed games.