修復無法開啟Windows Defender的問題
Fix Unable to turn on Windows Defender: Windows Defender is an inbuilt antimalware tool that detects virus and malware on your system. However, there are some instances when users experience that they are unable to turn on Windows Defender in Windows. What could be the reasons behind this problem? There are many users who explored that installing any third party antimalware software cause this problem.
Also, if you go to Settings > Update & Security > Windows Defender then you will see that the Real-time protection in Windows Defender is turned on but it’s greyed out and also everything else is turned off and you can’t do anything about these settings. Sometimes the main issue is that if you have installed a 3rd party Antivirus service then Windows Defender will shut itself off automatically. No matter what reasons are behind this problem, we will walk you through the methods to solve this problem.
Why can’t I turn on my Windows Defender?
One thing we need to understand that Windows Defender provides complete protection to our system. Therefore, not able to turn on this feature could be a serious problem. There are many reasons for you not being able to turn on Windows Defender in Windows 10 such as third-party Antivirus might be interfering, Windows Defender is turned off by group policy, incorrect date/time issue, etc. Anyway, without wasting any time let’s see How to fix the underlying cause of this issue using the below-listed troubleshooting guide.
Fix Unable to turn on Windows Defender in Windows 10
確保建立一個還原點，以防出現問題。
Method 1 – Uninstall any third-party Antivirus software
One of the most common causes of Windows Defender not working is third-party antivirus software. Windows Defender automatically shuts itself down once it detects any third party anti-malware software installed on your system. Therefore, you need to first start uninstallation any third party antimalware software. Moreover, you need to make sure that uninstallation is done properly all residue files of that software otherwise it will keep creating a problem for Windows Defender to get started. You can use some uninstaller software that will remove all remnants of your previous antivirus. Once the installations finished, you need to restart your system.
Method 2 – Run System File Checker (SFC)
Another method that you can opt for is system file diagnosis and repair. You can use command prompt tool to check whether Windows Defender files are corrupted. Moreover, this tool repairs all corrupted files.
1.按 Windows 鍵 + X 然後選擇 命令提示符（管理員）.
2.類型 SFC / SCANNOW 並回車。
3.This process takes some time so be patient while running this command.
4.In case sfc command did not resolve the problems, you can use another command. Just type the below-mentioned command and hit Enter:
DISM /在線/清理圖像/ RestoreHealth
5.It will scan thoroughly and repair corrupted files.
6.After completing these steps, check if you’re able to fix Can’t Turn ON Windows Defender issue or not.
方法 3 – 執行乾淨啟動
Sometimes there are some third party applications cause this problem, you can easily find those ones by performing the clean boot function.
1.Press Windows + R and type “MSCONFIG” 並按Enter鍵。
2.On the system configuration Window, you need to navigate to 服務標籤 where you need to check to 隱藏所有Microsoft服務 並點擊 全部禁用 按鈕。
3.導航至 Startup section 並點擊 打開任務管理器。
4.Here you will locate all startup programs. You need to 右鍵單擊 on each program and 禁用 all of them one by one.
5.After disabling all startup applications you need to come back to the system configuration window to save all the changes。 點擊 確定。
6.You need to reboot your system and check if you’re able to Fix Can’t Turn ON Windows Defender issue 或沒有。
To zero in on the issue you need to perform clean boot using this guide and find the problematic program.
Method 4 – Restart Security Center Service
Another method to get your Windows Defender problem solved is restarting security center service. You need to activate and ensure that certain services are enabled.
1.Press Windows + R and type SERVICES.MSC 並按Enter鍵
2.Here you need to search for 安全中心 進而 右鍵單擊 on Security Center and choose 重新啟動 選項。
3.Now simply restart your device and check if the problem is solved or not.
Method 5 – Modify your registry
If you are still finding the problem in turning on the Windows Defender, you can opt for this method. You just need to modify the registry but before doing so make sure to create a backup of your Registry.
1.Press Windows + R and type 註冊表編輯器. 現在按 Enter。
2.Once you open the registry editor here you need to navigate to:
HKEY_LOCAL_MACHINESOFTWAREP策略MicrosoftWindows Defender
3.Select Windows Defender then in the right window pane find DisableAntiSpyware DWORD. Now double click this file.
4.Set the value data to 0 and click OK to save the settings.
注意： If you’re facing permission issues then right-click on Windows Defender的 並選擇 權限。 Follow this guide in order to take full control or ownership of the above registry key and again set the value to 0.
5.Most probably, after doing this step, your Windows Defender will start working on your system properly without any problem.
方法6 – Set Windows Defender Service to Automatic
注意： 如果 Windows Defender 服務在服務管理員中顯示為灰色，則 關注這個帖子.
1.按Windows鍵+ R然後輸入 SERVICES.MSC 並按Enter鍵。
2.在「服務」視窗中找到以下服務：
Windows Defender防病毒網絡檢查服務
Windows Defender防病毒服務
Windows Defender 安全性中心服務
3.雙擊它們中的每一個並確保它們的啟動類型設定為 Automatic 自動錶 如果服務尚未運行，請按一下「啟動」。
4.單擊應用，然後單擊確定。
5.重啟你的電腦以保存更改，看看你是否能夠 Fix Can’t Turn ON Windows Defender issue.
方法7 – Set Correct Date & Time
1。點擊 日期和時間 在工作列上，然後選擇“日期和時間設置“
2.如果在 Windows 10 上，則使“自動設定時間“要”on“
3.對於其他人，點擊“互聯網時間”並勾選“自動與互聯網時間服務器同步“
4.選擇伺服器“time.windows.com”，然後按一下更新和“確定”。您不需要完成更新。只需按一下“確定”即可。
Again check if you are able to Fix Windows Defender Does Not Start issue or not, if not then continue with the next method.
Method 8 – Run CCleaner and Malwarebytes
2.運行惡意軟件字節 並讓它掃描您的系統是否有有害檔案。
3.如果發現惡意軟體，它將自動刪除它們。
4.現在運行 CCleaner 在「Windows」標籤下的「清理」部分中，我們建議檢查以下要清理的選項：
5.一旦您確定檢查了正確的點，只需單擊 運行更清潔， 讓 CCleaner 順其自然。
6.要清理系統，請進一步選擇「註冊表」標籤並確保選取以下內容：
7.選擇掃描問題並允許CCleaner掃描，然後按一下 修復選定的問題。
8.當CCleaner詢問“您想要對註冊表進行備份更改嗎？”選擇是。
9.備份完成後，選擇「修復所有選定的問題」。
10.重新啟動您的電腦以儲存變更並查看是否能夠 Fix Can’t Turn ON Windows Defender issue.
Method 9 – Update Windows Defender
1.按 Windows 鍵 + X 然後選擇 命令提示符（管理員）。
2. 在 cmd 中鍵入以下命令，並在每個命令後按 Enter 鍵：
“%PROGRAMFILES%Windows DefenderMPCMDRUN.exe” -RemoveDefinitions -All
“%PROGRAMFILES%Windows DefenderMPCMDRUN.exe” -SignatureUpdate
3.Once the command finish processing, close cmd and reboot your PC.
Method 10 – Update Windows 10
1.按 Windows 鍵 + I 開啟“設定”，然後按“更新與安全“圖標。
2.現在，請確保從左側窗格中選擇 Windows更新。
3.下一步，點擊“檢查更新”按鈕，讓 Windows 下載並安裝任何掛起的更新。
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Hopefully, above mentioned all methods will help you to Fix Unable to turn on Windows Defender in Windows 10 Issue. However, you need to understand that these methods should be followed systematically. In case you have more questions related to this problem leave your comments below.
