Remove a Virus on Windows for Free, Step by Step
A PC that suddenly crawls, pop-up ads that appear from nowhere, a browser home page that has been swapped out, a fan spinning at full tilt for no reason: the culprit is often malware. The good news is that in the vast majority of cases you can remove it for free, using tools that already ship with Windows. Here is the complete method, in the right order.
Spotting the signs of an infection
No single symptom is proof on its own, but a cluster of them is telling. Be suspicious if you notice several of these at once:
- Sudden slowdowns with disk or CPU pinned at 100% while idle.
- Ad windows or browser tabs that open by themselves.
- Home page or search engine changed without your consent.
- Unknown programs installed and browser extensions you never added.
- Antivirus switched off and impossible to turn back on.
Step 1: stop it from spreading
First, disconnect from the internet (turn off Wi-Fi or unplug the cable) so the malware cannot phone home or pull down more payloads. If the PC is very unstable, restart into Safe Mode with Networking: open Settings > System > Recovery > Advanced startup, then Troubleshoot > Advanced options > Startup Settings > Restart, and press option 5. Safe Mode prevents most malware from loading at boot.
Step 2: run a full scan
Windows includes a solid, free antivirus: Windows Security (Microsoft Defender). Open it via Settings > Privacy & security > Windows Security, then Virus & threat protection. Click Scan options and choose Full scan: it inspects the entire drive, not just recent files. Allow 30 to 60 minutes, let it finish, and quarantine everything it flags.
Step 3: the offline scan, your decisive weapon
Some malware (rootkits) hides while Windows is running. The countermeasure is built in: under Scan options, choose Microsoft Defender Offline scan. The PC restarts into a minimal environment and inspects the system before Windows loads, neutralising threats that would otherwise be impossible to shift. This is the step too many people skip.
A quick scan reassures you; a full scan followed by an offline scan actually cleans the machine.
Step 4: uninstall the junk and clean the browser
Open Settings > Apps > Installed apps and sort by install date. Uninstall any program you do not recognise or never wanted (toolbars, "optimisers", fake media players). In your browser, open the extensions list and remove anything suspicious, then reset the home page and search engine and clear the cache. Many "infections" are really just adware nested inside the browser.
Step 5: check startup items and scheduled tasks
Malware likes to come back after a reboot. Open Task Manager (Ctrl+Shift+Esc), go to the Startup tab and disable unknown entries. Also glance at Task Scheduler: an oddly named task that relaunches a file from a temporary folder is a classic warning sign.
Once it is clean
- Change your important passwords (banking, email) from a clean device, as they may have been captured.
- Update Windows: most infections exploit flaws that have already been patched.
- Check your backups so you never have to pay if it happens again.
The shortcut: let Yuna7 do it
Chaining a full scan, an offline scan, an app cleanup and a browser reset takes time and assumes you know where to look. With Yuna7, you simply describe the problem ("my PC is slow and showing ads"): the AI inspects the system, runs the right scans, quarantines what needs quarantining, removes unwanted programs and extensions, and confirms nothing persists at startup. Every action is logged, and you approve anything sensitive.
