Learn how to fix your game here.
A: Install the DLCs.
A: Install the DLCs, or if you are 100% sure you installed them right, just restart your game.
A: Install DirectX.
A: Verify your game files through Steam, or use the IW6x Repair Guide.
A: Make sure IW6x.exe is in your Ghosts directory. If this still happens, verify your game files using Steam or use the IW6x Repair Guide