Fixnúť Defender W10/11, tutorialčekov jesto plný net:

https://www.pcerror-fix.com/top-7-solutions-to-fix-windows-defender-does-not-start

Ak máš Pro verziu Windows, kukni do politiky Gpedit.msc (návod si nájdi na nete, ako sa spustí/vypne Defender.

Okopči text po perforkou do Notepad.exe, ulož ho, premenuj príponu napr.: def_fix.reg, ulož súbor tebárs na Plochu. Klik myšou na *.reg, roletka kontextového menu - Merge, čiže spojiť, pridať do Registrov.
Reštart PC.
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Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender]
"DisableAntiSpyware"=dword:00000001
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]
"SecurityHealth"=-
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\StartupApproved\Run]
"SecurityHealth"=-

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SecurityHealthService]
"Start"=dword:00000002

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\wscsvc]
"Start"=dword:00000002

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender]
"DisableAntiSpyware"=dword:00000000
"DisableRealtimeMonitoring"=dword:00000000
"PUAProtection"=dword:00000001

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\MpEngine]
"MpEnablePus"=dword:00000001

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender]

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Real-Time Protection]
"DisableBehaviorMonitoring"=dword:00000000
"DisableOnAccessProtection"=dword:00000000
"DisableScanOnRealtimeEnable"=dword:00000000

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender Security Center\Systray]
"HideSystray"=dword:00000000

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender Security Center\Notifications]
"DisableEnhancedNotifications"=-