Windows lost

This month I installed Obsidian 0.9.3, which worked fine. I am using it on windows. Just starting today I can not find the Obsidian windows anymore: the icon in the taskbar opens, is clickable, but the main windows can not be seen anywhere.

I tried to install 0.9.6 on top of it, but things don’t change.

This behaviour is not to be seen for other windows applications, so I think it is some issue with the layout of the workspace. Is there perhaps a shortcut for restoring the layout? Any other hint?

Topics may be closed:
Today it is working, don’t know what caused the difference.

Sorry for the hassle!