Windows 10 can lose activation for numerous reasons, especially after a Windows Update. Here are the steps you can take to reactivate Windows.
1: Run the Activation Troubleshooter
Press the Windows Key + S and begin typing activation and click on See if Windows is activated. You should see the troubleshooting link, but only if Windows 10 or 11 sees a problem. Years ago, we'd never suggest running a troubleshooter, but in Windows 10 & 11, many of them are now functional.
2: Enter Your Product Key and Activate Manually
The most obvious step is to enter your product key and activate it again. This step assumes you have your product key. If not, it could be embedded in your BIOS/UEFI firmware. To check that, open a Command Prompt or PowerShell as admin and type in:
wmic path SoftwareLicensingService get OA3xOriginalProductKey.
Press the Windows Key + S and begin typing activation and click on Activation settings.
Click on . Enter a Product Key and enter your 25 digit product key. Windows should be active once you enter the key.
3: Contact Microsoft Support
Believe it or not, Microsoft support is easy and usually quick to use. While most geeks prefer to find the solution themselves, sometimes support is the solution. There are a few ways to contact support, but we prefer two.
A complete list of worldwide support phone numbers can be found here or by searching for Microsoft support phone numbers.
While many guides suggest you now roll back, use System Restore, or even clean install, we're not fans of any of these steps. The point is to get Windows activated, not wipe everything out, and we hope we accomplished that for you? The simple fact is that your computer worked and had a valid key, so we're confident the three steps above should solve your problem.