Windows Security provides a starting point if you suspect malware or want to check protection status.
Check the dashboard
Search Start for Windows Security, then open Virus & threat protection. Review warnings and the active provider. If another antivirus product is installed, its provider may be shown instead.
Run a suitable scan
Begin with Quick scan. For a wider check, open Scan options and select Full scan. Save your work before running Microsoft Defender Offline scan because it restarts the PC.
Handle results carefully
Follow the security app’s instructions and review Protection history. Do not turn off protection or add an exclusion at the request of a pop-up or unknown caller. Contact your employer’s IT team if company data may be involved.
Further reading: Microsoft Support: virus and threat protection.