Windows 10: .Net error difficult to solve problems in Win 10 pro

I have a problem in my system of winning 10 with .NET framework.
Please read carefully. I will try to write what has been tried so far and answer any questions you may have:
This happened after winning 10 update of the 1803 version on Tuesday. There is no restoration point.
Machine: Win 10 pro – 1809.
No more Windows updates available.
The system says that .NET is installed. When trying to install any available version.
But it does not appear in the list of Windows features correctly. "NET Environment", which is a strange entry, can not be activated.
The Windows feature seems to be broken.

All the .NET dependent software has stopped working and gives error messages. As for example the total security of Kaspersky.
Tried: Run sfc / scannow
Tried: the offline installation from the offline folder gives the following message.
All the DISM commands have been tested. Installation and restoration of NetFx3 / 4.
The NetFx3 / 4 function can not be activated (enable function) (online and from the folder).
Tried: network user administrator / active: yes
He also created a new administrator user in Windows and tried to install .NET with that user. The same mistakes.
I have used the verification tool win .NET framework, Microsoft. NET Framework Repair Tool, .NET cleanup tool.
Also, I can not access group policies
I have replaced the .cab files and tried to enable the function after that. It did not work as before.
I installed the 1809 update. The same problem after the last upgrade to win 10.
Installed preview of .NET 4.8. 100% fine installation. There are still no changes. I tried to install other previous versions of .NET
He made a second update in situ.

After the 4.8 preview I think that:
The error is in the Windows feature OR the group policy that I can not enter.

Microsoft level 3 could not help me.