This happened to me while using the desktop version of Quicken on my laptop. The application is open – yet I can see it anywhere on my display. This is most likely caused by having a secondary monitor attached at some point. But how do you recover when you don’t have a secondary monitor to plug into? See this tip below:
Click the icon in the taskbar to ensure that the program has focus. Then hold down the Windows key and press the right-arrow a few times. That should move the window across your screens and eventually bring it back onto the screen that is still active.