Turn on Windows Defender

  Complete the following steps to turn on Windows Defender on your device.

1. Select the Start menu.
2. In the search bar, type group policy. Then select Edit group policy from the listed results. The Local Group Policy Editor will open.
3. Select Computer Configuration > Administrative Templates > Windows Components > Windows Defender Antivirus.
4. Scroll to the bottom of the list and select Turn off Windows Defender Antivirus.
5. Select Disabled or Not configured. It might feel counter-intuitive to select these options because the names suggest that you're turning Windows Defender off. Don't worry, these options actually ensure that it's turned on.
6. Select Apply > OK.

Turn on real-time and cloud-delivered protection

Complete the following steps to turn on real-time and cloud-delivered protection. Together, these antivirus features protect you against spyware and can deliver fixes for malware issues via the cloud.

1. Select the Start menu.
2. In the search bar, type Windows Security. Select the matching result.
3. Select Virus & threat protection.
4. Under Virus & threat protection settings, select Manage settings.
5. Flip each switch under Real-time protection and Cloud-delivered protection to turn them on.

If you don't see these options on your screen, they may be hidden. Complete the following steps to make them visible.

1. Select the Start menu.
2. In the search bar, type group policy. Then select Edit group policy from the listed results. The Local Group Policy Editor will open.
3. Select Computer Configuration > Administrative Templates > Windows Components > Windows Security > Virus and threat protection.
4. Select Hide the Virus and threat protection area.
5. Select Disabled > Apply > OK.

Update your antivirus definitions

Complete the following steps to update your antivirus definitions.

1. Select the Start menu.
2. In the search bar, type Windows Security. Select the matching result.
3. Select Virus & threat protection.
4. Under Virus & threat protection updates, select Check for updates. If you don't see this option on your screen, complete the first set of steps in Turn on Real-time Protection. Then try checking for updates again.