DirectX is a suite of multimedia technologies required by many Windows games. If your PC doesn't have the right version of DirectX installed, your game might not work properly.
Usually, when you download a game from the website, it will automatically install the correct version of DirectX needed to play it, though this isn't always the case. Uninstalling and reinstalling your game will usually fix the issue; however, if you continue to receive an error message that you are missing or have the wrong version of DirectX, you can click HERE to navigate to the Microsoft support site, where you can download and install a number of DirectX runtime libraries that should fix your issue.