I believe you're referring to
this thread. However, if you have the updated version (updated in 2014), this file is no longer available to change, and if you have removed the game from your computer at any time (or changed computers) , that would explain why it's giving you problems now. The technical "trick" listed in the thread above is simply if you cannot change the full/windowed setting in the game itself.
I can tell you that the precise issue that you're referring to is most often caused by the resolution, and if you can access the menu, simply click on the options/settings and click full screen and see if that resolves the issue.