The user presses the back button on the screen, it changes the state, goes to the game instance, switches on the state. If Main Menu, then remove all widgets, see if the widget variable is valid, if not, make it valid, if yes, then add to view port.
I am happy to hear that it sounds like you have resolved your issue. I will be marking your last post as the answer to this thread. If this issue returns please feel free to reopen this thread by providing any additional information you may have in a reply.