How to Get Rid of a Virus on a Windows PC

First, you need to determine if your computer has a virus at all. Sluggish performance is a sign of malicious code. If your web browser suddenly looks different or automatically redirects to an unfamiliar site, that’s a good indication that malicious programs are at play.

Unstable behavior, such as frequent crashes, can also signal a problem. Additionally, if you try to access files and receive messages saying they're corrupted, that's another red flag.

If you suspect your computer has a virus, run antivirus software to identify and remove it.

­Antivirus software is practically a requirement for anyone using the Windows operating system. While it's true you can avoid computer viruses if you practice safe habits, the truth is that the people who create malicious apps and programs are always looking for new ways to infect computer systems.

A few malware variants will try to block you from downloading antivirus software. If that's the case, you may need to download the software on another computer and transfer it to disk or a flash drive.

If you don't have any antivirus software, now's a good time to purchase or download an application. There are several different antivirus programs on the market — some are free and some you have to purchase. Keep in mind that free versions often lack some of the nicer features you'll find in commercial products.

Assuming your antivirus software is up to date, it should detect malware on your machine. Most antivirus programs have an alert page that will list each and every virus or other piece of malware it finds. Write down the names of each malware application your software discovers. (More on this in a bit.)

Many antivirus programs will attempt to remove or isolate malware for you. You may have to select an option and confirm that you want the antivirus software to tackle the malware. For most users, this is the best option; it can be tricky removing malware on your own.

If the antivirus software says it has removed the malware successfully, shut down your computer, reboot and run the software again. This time, if the software comes back with a clean sweep, you're good to go.

If the antivirus software finds different malware, repeat the previous steps. If it finds the same malware as before, you might have to try something else.

Two's a Crowd

If one antivirus program is good, two is better, right? Wrong. This type of software tends to use up a large percentage of the processing power of your computer system.

Running more than one antivirus program will slow your computer to a crawl and possibly cause it to crash. Not all antivirus programs are compatible with one another, which can make your computer even more unstable.

If you can't access your antivirus software or keep seeing the same malware pop up scan after scan, start your computer in Safe Mode. Many computer viruses store files in your Windows registry folder, which acts like a database of instructions and tells your operating system important information about the programs on your computer.

It can also tell viruses to activate as soon as the operating system loads. Starting your computer in Safe Mode allows you to work with your machine using only the core elements of the Windows OS.

Try running your antivirus software in this mode. If new malware is detected, you may have found a solution. Some malware exists solely to download and install other malware on your machine. Removing all these applications can significantly improve your system's security.

Research the Malicious Software

If your antivirus software can't remove the virus on its own, additional research is needed for manual removal. You've already written down the names of all the malware applications that your software discovered. Now it's time to research each of those files online using the same internet security firm that produced your antivirus software.

Different firms sometimes give the same virus different names, so using the same firm's resources ensures consistency. Most internet security firms list all the files associated with a particular virus and indicate where to find them. You may need to search extensively to locate each file.

Before deleting any files, save a backup copy of your registry folder. Accidentally deleting the wrong file can make it difficult or impossible to run your computer properly.

Now delete all the infected files associated with the malware on your list. Once that's done, reboot your computer and run your antivirus software again. Hopefully, nothing else will be detected.

Finally, update your login information for your various online accounts. Some malware includes keylogging software that can send your passwords and other information to a remote user. It's better to be safe than sorry.

Give Viruses the Boot (Disk)

Some antivirus software allows you to create a special boot disk. This disk can be invaluable when your computer is infected with particularly stubborn malware that prevents normal operation. The boot disk enables you to start your computer from a clean, secure environment, bypassing the infected operating system.

After creating a boot disk, reboot your computer with the disk in the drive. Your computer will read from the disk, load a limited operating system, and run a virus scan. This method can help you bypass the malware's code and disable it, effectively removing the infection and restoring your system to a functional state.

To avoid computer viruses on a Windows computer, follow these simple guidelines that mostly rely on common sense:

If you cannot delete a malware infection despite trying various methods, it might be time to perform a complete system wipe on the infected computer. This involves formatting your hard drive and reinstalling the operating system.

A complete system wipe is often a last resort because it will delete all of your information, including programs, settings and personal files. Therefore, it is crucial to back up any important, virus-free files before you start. You can use external storage devices or cloud services for this purpose.

Performing a system wipe can be time-consuming, as you will need to reinstall the operating system, update it, reinstall all your applications and restore your data. However, this method ensures that all traces of malware are removed, giving you a fresh start with a clean slate.

After a system wipe, it is essential to immediately install antivirus software and update it to the latest version to protect your newly restored system from future infections.

This article was updated in conjunction with AI technology, then fact-checked and edited by a HowStuffWorks editor.