You can search windows update history to see if there was one that sneaked past you. If there was one, you can use the restore point created and see if it was something in the update that did it. There has been a number of issues in 8 and 8.1 where windower will stop working (sometimes after an update) and will not work again without a full reinstall of the OS.
I know 10 is not 8, but I am sure most of the architecture is the same. There was also another thread in the ffxiah windower forum that was about this same issue and it did not appear to be resolved. I am not saying this is the same problem you have, but it may be worth a try
if there was an update.
Otherwise, I would say check to make sure you have windows 10 compatable drivers for your video card, but if vanilla works, I would think you do. You can try going into config and see if the resolution is blanked out...and if it is adjust it with your settings.
If nothing works, you can create a post here:
Windower/Issues
The dev team for windower has said they will see a support issue here much faster than if it is on ffxiah.
Good luck.