The Microsoft Defender Offline scan will automatically detect and remove or quarantine malware. Learn how to remove malware from your PC. Use Microsoft Defender Antivirus in Windows 10 or Windows 11 to scan your PC for malware, viruses, or other threats.

If your system is asking you for your BitLocker recovery key, the following information may help you locate your recovery key and understand why you're being asked to provide it. Important: Microsoft support is unable to provide, or recreate, a lost BitLocker recovery key.

If you're unable to activate Windows 11, the Activation troubleshooter could help. To use the troubleshooter, select Start > Settings > System > Activation , and then select Troubleshoot . Open Troubleshoot settings. You must be signed in as an administrator to use this option.

Learn how to activate Windows using a product key or digital license, check your activation status, and link your Microsoft account.

If some Windows functions aren't working or Windows crashes, use the System File Checker to scan Windows and restore your files. Though the steps below might look complicated at first glance, just follow them in order, step-by-step, and we’ll try to get you back on track.

Locate your product key for Windows 10 or Windows 11. Depending on how you got your copy of Windows 10 or Windows 11, you'll need either a 25-character product key or a digital license to activate it.

Activation helps verify that your copy of Windows is genuine and hasn’t been used on more devices than the Microsoft Software License Terms allow. This article will help you troubleshoot and fix common activation errors in Windows. For help finding your product key, see Find your Windows product key.

Each release of the tool helps detect and remove current, prevalent malicious software. This malicious software includes viruses, worms, and Trojan horses. Microsoft uses several metrics to determine the prevalence of a malicious software family and the damage that can be associated with it.

If you already redeemed a product key, you're simply reinstalling the apps, or you know you have an assigned license through work or school, you can skip ahead and go to the section sign in to download and install Microsoft 365 or Office.

Activate a brand new Office product key. Troubleshoot activation errors. Activate Microsoft 365 or a non-subscription version of Office. When you start an Microsoft 365 app that's not activated, you'll be prompted to sign in to Microsoft 365.