I received this PC as a hand-me-down from my uncle. He originally created a Windows account for me, but I already had my own Microsoft account, so I tried to remove his account. The removal process took several months. Later, the computer became very slow, so I used the built-in reset option. Now Windows keeps trying to sign me into the old account, but the PIN no longer works. It displays: "The User Profile Service service failed the sign-in. User profile cannot be loaded." Is there a way to fix this, or should I reinstall Windows completely?
2 Answers
The most reliable solution is a clean Windows installation instead of using the built-in reset feature. Create Windows installation media on another computer with a USB drive, boot this PC from that USB, delete the existing Windows partitions during setup, and install Windows again. This will erase the drive, so back up anything important first.
A fresh reinstall should remove the damaged user profile and any leftover account configuration. Download the official Windows installation tool, make a bootable USB drive, start the problem PC from it, and choose a custom installation. Afterward, sign in with the Microsoft account you actually want to use and reinstall your programs.

How do I wipe the PC and start the installation from a USB drive?