Every so often we hear from a Mac user with a seemingly impossible problem: a document window in some app is opening somewhere outside of the screen so it’s effectively invisible and they can’t work with it in any way.
Closing (with File > Close) and reopening the window or quitting and relaunching the app, or even restarting the Mac won’t usually help because the app will reopen the window in the same off-screen position.
The solution is to try various commands in the app’s Window menu such as Tile, Move, or Zoom. (You may need to choose View > Show All Tabs to get the tab-related commands.) The Window there will vary by App but with luck one of them will bring your errant window back on screen.