Here is the Step by Step Tutorial for Verifying Your PC Game Cache Thorough Steam Menus:
Validate your game files to fix most of the problems:
- Restart your computer and launch Steam
- From the Library section, right-click on the game and select Properties from the menu.
- Select the Local files tab and click the Verify integrity of game files... button.
- Steam will verify the game's files - this process may take several minutes.