How to Reinstall Windows Defender on Windows 11

Are you looking for a way to reinstall Windows Defender on Windows 11? This guide will show you how to do this via the PowerShell command line. Read on if you're interested!


By Miya Updated on November 30, 2023

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How Can I Reinstall Windows Defender on Windows 11?

Reinstall Windows Defender Windows 11


“I recently upgraded to Windows 11 and was using a free trial of my McAfee antivirus software. My trial period ended and I uninstalled the software in hopes of getting back to using Windows Defender. After navigating to Windows Security settings, I found the menu was blank with no information. I don't even have the Microsoft Defender service in my service menu, which is worrisome. This leads me to believe that the Microsoft Defender software has somehow been corrupted or removed from my computer. My computer is currently unprotected and I was wondering if there is any way I can reinstall Windows Security on Windows 11? Any help would be appreciated!


- Question from Microsoft Community


Microsoft Defender is a free built-in antivirus for the Windows operating system. It was known as Windows Defender until May 10, 2020, and now also appears as Windows Security in the latest Windows 10 update.

Windows Defender provides Windows users with a convenient antivirus solution. It has a bunch of security features that provide online protection for your device against spyware, adware, ransomware, and other malware. Windows Defender offers 4 scanning modes: Full Scan, Quick Scan, Custom Scan and Offline Scan.

Detailed Steps to Reinstall Windows Defender on Windows 11

Although Windows Defender has been the default antivirus pre-installed in Windows, some users may find that the application is missing after certain events, such as updating Windows or installing or uninstalling certain third-party antivirus software. For some reason, they may want to reinstall Windows Defender on Windows 11.

You can reinstall Windows Defender in Windows 11 via Windows 11 PowerShell or Windows Terminal. Please note that you will need administrator privileges to execute the command.

  1. Press Windows + S to open the search bar in the taskbar. Type PowerShell in the search box, then right-click on it and find the Run as administrator option.

Windows PowerShell

  1. When you open the Windows PowerShell window, copy and paste the following command and press Enter to reset Windows Defender to its original settings. This will allow you to reinstall Windows Defender on Windows 11.
  • Get-AppxPackage Microsoft.SecHealthUI -AllUsers | Reset-AppxPackage

Reset Windows Defender

  1. After the above command is executed, you can press Windows + I to open Settings. Then find Privacy & Security -> Windows Security. This should open Windows Security (Windows Defender settings) just like before.

Windows Security

  1. To further verify that Windows Defender is installed successfully, click the Open Windows Security button to open the Windows Security window. From there, you can manage your computer's security, such as virus protection, firewall, network protection, browser control, and more.

Security at a Glance

Back Up Your Computer for Quick Recovery on Windows 11

Many users may have experienced the disappearance of Windows Defender, especially after installing third-party antivirus software. When you want to use Windows Security again, you can reinstall Windows Defender on Windows 11 by the method provided above.

After you get the tool back, I recommend that you make regular backups of your computer. Every time you encounter a different problem, you need to find a different solution, which will consume a lot of your time and energy. Also, many users are not very proficient in using command line tools. If you have backed up your computer in advance, you can easily use the backup to restore your computer to its previous state.

AOMEI Backupper Standard is a practical Windows backup software that can meet all your daily backup needs. Let's see what it can do:

💖 Multiple backup methods. It supports you to backup system, files, disks, partitions, etc. You can choose the most suitable one according to your needs.
💖 Multiple backup destinations. All backup types support backup to internal or external hard drives, cloud drives, network locations, and NAS devices.
💖 Automatic backup. The software helps users back up data continuously, so you never miss any changes. You can choose the frequency of Daily, Weekly or Monthly.
💖 Create bootable media. If you have a problem with your computer and it doesn't boot properly, you can use the bootable media you created earlier to start your computer.

All Windows PC operating systems like Windows 11/10/8.1/8/7/Vista/XP are supported. However, if you are running Windows Server operating system, please turn to server backup software. Next, I will show you how to backup  Windows 11 via AOMEI Backupper. Take Disk Backup as an example, it will create a disk image of the specified hard disk, including the operating system, installed program, personal data, etc.

  1. Download, install, and launch AOMEI Backupper Standard.
Download FreewareWin 11/10/8.1/8/7/XP
Secure Download
  1. Launch this freeware on your computer, click Backup in the left panel, and then select Disk Backup.

Disk Backup

  1. Click “+ Add Disk” to choose the source disk that contains Windows 11.

Select Source Disk

  1. Select the destination location where you plan to store the backup images.

Select Destination Place

Tips✍: Before you start the backup, you can check the options "Options", "Schedule", "Scheme" in the lower left corner.
☪ Options: Here you can write comments for your backup tasks and modify the compression level of your backups. If you want to encrypt your backups, please upgrade to AOMEI Backupper Professional Edition.
☪ Scheme: You can enable this feature to delete old backup images to ensure that there is always enough space to save new backup images (available in the advanced version).

  1. After confirming all your settings, click Start Backup.

Start Backup


If you have the need to reinstall Windows Defender on Windows 11, you can follow the method provided in this article to complete the reinstallation with the help of command line tools. After you have fixed the problem, it is recommended that you create a backup of your computer using a free backup tool. This way, if you encounter any problems with the built-in software in the future, you can use this backup to restore your computer to its previous working state.

Miya · Editor
Miya has an excellent insight and receives professional and systematic technical training since joining AOMEI. She has a comprehensive understanding of computer issues, aiming at helping users troubleshoot all kinds of problems. A lot of computer users around the world have found her articles very helpful!