Figured out can help someone else.
My problem was that I couldn't install antivirus on Windows 10 build OS 10586.122
During installation, any time asked to restart the operating system and try again , it lasted indefinitely.
Solution : first you need to remove other antivirus applications. then go through start, settings , then select defender Windows there disable everything you can , then enable it , reboot and install avast safely . hope it will help someone else !