How to Check Your Computer For A Virus or Viruses For Free

by Bonnie Crowe

Your business relies on a fast and efficient computer. When your computer gets a bug, it’s a lot like when you do. Your computer gets bogged down and it processes things much slower. You must detect, isolate and eliminate the infection before it spreads. Computer viruses can not only contaminate your system, they can spread through your network and infect every computer connected to it. This can ruin financial data and compromise sensitive information. There’s no need to spend big bucks to determine if your computer has a virus because Windows Defender is built into your operating system and can scan your computer for free.

Windows Defender


Click the Windows “Start” button, type “defender” into the Search field and click "Windows Defender" from the search results.


Click “Scan.”


If a virus is found, Windows Defender will give you instructions for removing it.

Windows Defender Offline


Launch a Web browser and navigate to the Microsoft website to download Windows Defender Offline (see Resources). Do this with a computer that is free from infection.


Insert a blank CD, DVD or a USB flash drive into your computer.


Click “Download Windows Defender Offline” and select the location where you want to save the file. Click “Save.”


Remove the external storage device with Windows Defender Offline from the computer you used to download it and insert it into the infected computer. Reboot the PC with the infection.


You will be prompted to press a key to boot the computer. Use the arrow key to navigate to the location of the Windows Defender Offline program. The program will launch and begin scanning.


  • check Make sure your computer has the most recent updates. Visit Windows Update often.


  • close If your computer is already infected by a virus, you may not be able to run the latest security update from Windows until you get rid of the bug.
  • close Not all programs can detect all viruses. If you have found a bug resistant to the methods you’ve tried, download another free anti-virus program. A list of free scanners and anti-virus removers can be found on the Microsoft website.

About the Author

Bonnie Crowe is a mother of two teenagers; a teacher and author of children's books, curriculum and articles on English grammar, literature, technology, art, parenting and career guides for high schoolers. She's a former director of AOL Parenting, a member of SCBWI, and a graduate from the University of California,Berkeley.