Please try the following:
- Exit Steam.
- Right-click on Steam icon.
- Left-click on "Run As Administrator".
- Right-click on the game in Steam Library. Click on "Properties".
- Select "Local files" tab and click on "Verify integrity of game cache files" button.
- Please wait, the process can take several minutes.
- If the issue persists, reboot your PC and try one more time from step 2.