This article explains how to activate Windows Defender on a PC. If for any reason you have knowingly disabled it after restarting your computer for the last time, you can manually reactivate it from the Windows Security screen of the Settings app. If you recently installed a third-party antivirus program that automatically disabled Windows Defender, you'll need to uninstall it before you can re-enable it.
Steps
Method 1 of 2: Enable Windows Defender
Step 1. Make sure Windows Defender has been disabled
If you deactivated the program after restarting your computer for the last time, it will remain in that state until you manually reactivate it or restart your system. To resolve this issue, please follow the instructions described below.
If you haven't manually disabled Windows Defender since the last time you restarted your computer, it most likely was disabled by installing a third-party antivirus program. To be able to reactivate Windows Defender, you will first need to uninstall the antivirus program you previously installed
Step 2. Access the "Start" menu by clicking on the icon
It features the Windows logo and is located in the lower left corner of the desktop.
Step 3. Launch the Settings app by clicking on the icon
It features a gear and is located at the bottom left of the "Start" menu. The "Settings" menu will be displayed.
Step 4. Click on "Update and Security"
It features a circular icon depicting two curved arrows.
Step 5. Click on the Windows Security tab
It is listed along the left side of the page.
Step 6. Click on the Virus & threat protection option
It is displayed in the center of the window.
To continue, you may need to maximize the "Windows Security" window by clicking on the square icon located in the upper right corner of the window
Step 7. Click the Manage Settings link
It is displayed within the "Virus and threat protection settings" section located in the center of the window.
Step 8. Click on the "Disabled" slider
visible in the section "Real-time protection".
It is located at the top of the appeared card.
Step 9. Click the Yes button when prompted
This will re-enable Windows Defender protection.
Method 2 of 2: Uninstall a Third Party Antivirus Program
Step 1. Determine if you have intentionally installed the antivirus program
If you installed it manually, you should know its exact name. If not, it is very likely that the antivirus was installed as an add-on during the installation of another program. In this case you will have to go through the list of all the software installed on your PC looking for the ones you don't know.
Step 2. Access the "Start" menu by clicking on the icon
It features the Windows logo and is located in the lower left corner of the desktop.
Step 3. Launch the Settings app by clicking on the icon
It features a gear and is located at the bottom left of the "Start" menu. The "Settings" menu will be displayed.
Step 4. Click on the App tab
It is displayed in the center of the "Settings" window.
Step 5. Sort the list by installation date if needed
If you don't know the name of the program you want to uninstall, you can narrow down the search by looking at the list of programs that were recently installed. Click on the "Sort by" drop-down menu and click on the option Installation date.
If you already know the name of the antivirus program to uninstall, you can skip this step
Step 6. Find the antivirus program to uninstall
Scroll down the list until you find the program you want to remove from your computer.
If you didn't intentionally install antivirus software, you will most likely need to locate the program that did it automatically and that disabled Windows Defender. In this case it should be listed at the top of the list
Step 7. Click on the name of the program in question
A box with the button inside will be displayed Uninstall.
Step 8. Click the Uninstall button
It is displayed in the lower right of the pane where the program name is visible.
Step 9. Click the Uninstall button when prompted
The program uninstall wizard window will appear.
Step 10. Follow the instructions that will appear on the screen
Go through all the uninstall wizard screens, making sure to select the "Delete all files" (or similar) option in case you are asked if you want to keep configuration files or related apps.
Step 11. Delete all other associated programs
Some antivirus automatically install add-ons, for example to manage security while browsing the web. If there are other programs in the list that were created by the same developer who created the antivirus under consideration or that have a similar name to the software you just uninstalled, remove them from your computer before continuing.
Step 12. Restart your computer
Access the menu Start by clicking on the button
click on the icon Stop
then click the option Reboot the system. Your computer will restart normally, and after the restart is complete, Windows Defender should be running again.
