it was pretty simple at least :-D
I noticed, that my monitor was not plugged in to the graphiccard.
So I just switched the Kabel to the other HDMI (I didnt know bevor that I have 2...)
Thats it.

Oh my god! I found the solution! you can close the task. Thank you anyway.

What can I do now? I tried so much but nothing worked. Can not working on my Projects anymore.
Thats so sad, because this program is amazing!
Do you have another idea to make it work again?
I've also de- and reinstalled - doesent help.

I updated the intel driver and changed the setting to high performance via Windows (Option 1 not available).
But still dont work :-(
But now a different Error: the blender debug log now says "Error: EXCEPTION_ACCESS_VIOLATION Address : 0x0000000000000000"

I hope this are the rigth files.