Pycharm Graying Out the Run Button

If your run button is suddenly greyed out and no longer green, try the following:

1.) open another repository / project

    File > Open > select project > OK

2.) If you have the pop-up to choose "This Window or "New Window", chose "This Window"

3.) Open the repository / project that had the greyed out run button

4.) It should be green by now

From: https://stackoverflow.com/questions/8364483/why-is-the-run-option-disabled-on-pycharm