Ok, I will try it.
First, the Windows Startbar was buggy and appeared wrong. (Like here
https://www.windows10forums.com/threads/windows-10-gui.4514/)
Then someone told me it may help to reinstall the last program I installed. So i did it and everything worked like before (Only had to add the Windows 10 Docks/Squares/icons back on the Starbar)
But as I reboot my PC other Windows GUI bars don't work (see pictures)
I can NOT right click any program in the taskbar. There only appears a blank box. Before I could choose options like "pin to taskbar", "close window" etc. now there are only these two dark-/grey stripes (picture2).
The second GUI problem is the volume level icon. I selected the right playback item and the sound works perfect but I can't reduce/increase the volume with this icon (Only with my keyboard shortcuts). And if you can see the volume icon look really strange it's "muted" and "at the highest volume" at one time.
I could change the device with the little arrow up before now the bar is empty.
But if i use the old "Windows Volume" (e.g if i change it in the Regedit) everything works.
I have similar problems with the Windows 10 notifications. First, there was always a message like "screenshot saved" now it's empty
Sorry that I didn't explain my problem earlier
Thanks for help
EDIT:
I tried to "
sfc /scannow" like your explanation in the other thread but windows give me only the error: "Windows could not start the repair service"