Having you tried something like SlimCleaner to wash down your Windows 10 (especially emptying the Windows/Temp folder) and restarting it? Also, have you tried "Trashing the Preferences" of InDesign? This trashing/resetting topic is permanently posted at the head of this InDesign forum.
It is likely the window has found it's way outside the boundaries of your monitor. Typically this happens when you were using a two-monitor setup but are now running with only one. To check if you have two displays defined even if you aren't actually looking at two displays, find a clear area on the desktop, right click and choose "Display Settings". That'll show you how your displays are arranged ... valuable information if the window has found it's way to the other one. If you DO have two displays defined and the second isn't physically available, then do a "Windows Key+P" to get the "Projection" panel to open up. At the top of that choose "PC Only" and that should effectively shutdown the second virtual display and bring everything to the main.
But since you just converted to Win 10 it's also possible that the "display scaling" has mapped a window that used to be close to the edge right off the side. There are a couple of ways to go. If you are using your monitor at a resolution way less than it's "native" resolution, try setting it to it's native resolution (by using "Display Settings as mentioned above) and see if the window becomes visible. Then drag it back to the center of the screen and go back to your preferred resolution.
If this isn't the case, you have to try to "move" the window back onto the monitor...which can be frustrating if you have no idea where it might be. To do this you hover over the task bar image of the window that pops up and right click. Click the "move" menu item. The mouse cursor will disappear: it's really been positioned on the title bar of the wayward window. Now press either the left or right arrow key once, then left-click and and HOLD. Now you drag it to the center of the monitor. Which way do you drag? Ha! That's where the guesswork starts.
If you've never defined a second monitor, it might be possible to get the window back by clicking on the "multiple desktops" Task bar icon (usually on the left side... it looks like two overlapping rectangles. Now you should see all your windows on that desktop portrayed in a grid. Hopefully the story editor is there. If it is, right-click on it and choose "snap left" or "snap right". With any luck that'll bring it back to one edge or another. It might even be worth trying even if you DID have a multi-monitor setup.
I'm still getting used to Windows 10 (which automatically updated without any permission from me!). On my new Windows 10 desktop, I can't left click or right click anymore. Just all those boxey shortcuts are there. And when I click the Windows start button, all I get is the desktop, not "All Programs" although there is a small icon on the desktop for All Programs.
My display was set to only 1 monitorr, and my resolution was correct. But I did play with those "Snap" settings (not sure exactly!) and voila! My Story is there!
So thank you for your help!!
Whoa! Never thought it would come to that last desperation move! BTW Adobe has always had problems with the odd window getting lost somewhere. And BTW BTW now that you have touched the multiple desktops it's well worth learning how to take advantage of them to mimic multi-monitors when the situation calls for it (like ID and Word together).
I prefer the simplicity of ALT+Tabbing among several full-screen apps. On Mac, it's Command+Tabbing.