For information about other applications available, see Dell Knowledge Base article How to Identify and Repair Malware or Virus Infected Systems.
Windows Defender is integrated to Windows 10. No installation or subscription is required.
In Cortana or the search box at the bottom of the Start menu, type Defender.
From the results select Windows Defender Security Center. (shield icon)
This opens the Windows Defender Security Center window.
Under Scan History, you see the gray button for Quick Scan.
See the Microsoft Knowledge Base article for more information, including how to Schedule a scan in Windows Defender Anti virus
Move to the upper right and select Search type defender in the search box then select Windows Defender from the results.
Select Scan options and select the scan option you want to run.
Click Scan now.
Open Windows Defender Security Center
Click the arrow next to the help button (?) or the Shield icon from the left menu.
Click Check for updates
For help on updating your Microsoft anti-malware and anti-spyware software, see the Microsoft Malware Protection Center
If you receive an error message asking you to check for new definitions or advising that definition updates cannot be checked, downloaded, or installed. See Microsoft Knowledge Base article Security intelligence updates for Microsoft Defender Antivirus and other Microsoft antimalware
Try to update the Microsoft Windows Defender definitions.
Restart the computer and boot into Safe Mode
Scan for Malware with Windows Defender.
Restart the computer and check for any symptoms of infection.
If further scans show up clean, turn the system restore back on.
When the above is not possible, try running an Advanced Scan, preferably an Offline Scan of the system before running a Full Scan. (see the first section of this article)
For information about applications and settings for Microsoft products that help protect against virus infection see Microsoft Knowledge Base article - How can I help protect my PC from viruses?
No Cause Information is Available.