Windows 10 comes with built-in antivirus protection in the form of Windows Security (previously known as Windows Defender). If you suspect your device has a problem, you can use the Windows Security Centre to run a virus scan which could uncover any dangerous files.
You can open the Windows Security Centre from its icon in the system tray – look for a white shield. Alternatively, launch it by typing "Windows Security" into the Start menu. Prior to the Windows 10 October 2018 update, the app was called Windows Defender Security Centre, so open this if you're using an older Windows release.
From the app's home screen, click the "Virus & threat protection" tile to open the antivirus page. Click the "Quick scan" button under "Current threats" to run a scan of your device. This may take a while to complete but you can keep using your PC while it runs. You'll get a notification when the scan is finished.
Once the scan has completed, the "Current threats" screen will display the outcome of the scan. If threats were found, you'll be able to get their details using the "Threat history" button.
If the quick scan doesn't find any problems, you can run a more thorough check by clicking the "Scan options" link. Here, you can choose to run a "Full scan" which will check every single file, as well as any running programs. There's also an option to run a custom scan within directories you define – use this option if you've already identified a suspect file and want to confirm whether it's a threat.
Windows security has come a long way with Windows 10 and the built-in virus scanning is now quite comprehensive. Although it's still not the most robust solution, Windows Security is an adequate protection system as long as you remain savvy about potential threats – don't click suspect links in emails or on websites! Windows regularly runs quick scans in the background and continually monitors your device for new threats in real-time, so you shouldn't need to run manual scans on a regular basis.