First way;
Please run "regedit" as administrator
in Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender
and poof! there is it I can run my windows defender again!. There is 1 value when I saw it then when I turn it to 0 its okay again!.
Reboot...
if windows defender don't start
Second way;
Please run CMD as administrator and type these commands one by one:
Dism /Online /Cleanup-Image /RestoreHealth
SFC /scannow
SFC /scannow
