Check the Status of Steam's Files
If the issue persists, you may have issues with your local Steam files. You may refresh these files without deleting your game files. Please follow this process to refresh your Steam files:
Exit Steam.
Navigate to your Steam installation directory. (c:\program files\steam\ by default.)
Delete everything in that directory EXCEPT the following:
steam.exe
steamapps directory (All of Steam's game files are kept here.)
Restart Steam to test the issue.