Windows Central posted How to re-activate Windows 10 after a hardware change
A quote from the article:
Have you made hardware changes to your PC and now you can't activate? In this guide, we'll show you the steps to use the Activation Troubleshooter to re-activate Windows 10.How to re-activate Windows 10 after a hardware change @ Windows Central
When you make significant hardware changes, such as replacing the motherboard or hard drive, Windows 10 won't be able to identify your computer correctly, and as a result, the operating system won't activate.