Hi, Jon B
The screenshot confirms that the scan completed successfully and did not verify any threats. The “19 infected files” shown during scanning was therefore not the final detection result, but it is reasonable to perform a second check for reassurance.
Here are some suggestions you can try:
Open Windows Security > Virus & threat protection > Protection history. Look for any item marked Action needed, Quarantined, or Remediation incomplete. Protection History records actions taken by Microsoft Defender and keeps them for two weeks.
In Virus & threat protection, select Protection updates > Check for updates, then return to Scan options and run a Full scan using Microsoft Defender Antivirus.
If you still suspect an infection, run Microsoft Defender Offline scan from Scan options. Save your work first because the computer will restart. This scan runs outside the normal Windows environment and is useful for checking malware that may hide while Windows is running.
If both Defender scans are clean and Protection History shows nothing requiring action, there is no current evidence that the computer is infected.
Thank you for your patience in reading, I hope this information has been helpful to you.
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