I was trying to upgrade from Win7 to Win10 using the Windows Update tool (Media Creation Tool 1909.exe) to create a USB. Once it completed I launched it, but then closed it because I realized there were still files I needed to backup beforehand. After rebooting for another issue, Windows alerts came on my screen saying that my product key was invalid (I had successfully installed Win7 Ultimate using a guide on this site about 4 years ago). So my question is now, is it possible to fix this mess? My system has become quite unstable (after being perfect for almost 4 years).. I desperately need to repair my Win7 installation, but I think I would probably need to fix this licensing issue beforehand. How would I go about these tasks? Can anyone let me know their thoughts on this?