Verifying the cache files of the game can help to ensure that the installation of a game is up-to-date and if necessary repair any bad or corrupted game data.
To verify the cache files of your game please follow the steps below;
1. Load Steam
2. From the Library section, right-click on the game and select Properties from the menu.
3. Select the Local files tab and click the Verify integrity of game cache... button.
4. Steam will verify the game's files - this process may take several minutes.
5. Once the process is completed, the Check Window will automatically exit.