Hello,Neil
Welcome to Microsoft Q&A.
Thank you for describing your issue in such detail — I understand your situation. You mentioned that everyone uses local accounts; can you confirm if this applies to your Windows 11 device as well? The specific symptom seems to be a login loop where entering the correct password just returns you to the sign-in screen — is that correct?
I suggest trying the following repair options:
Option 1:Go to Settings (press Windows + I) → System → Recovery,
Then under “Fix problems using Windows Update”, click “Reinstall now”.
This option will preserve your apps, files, and settings.
Option 2: Perform an in-place upgrade
Go to the Download Windows 11 page.
Under “Download Windows 11 Disk Image (ISO)”, select Windows 11, and:
- After downloading the ISO file, right-click it and select Mount
- Open the mounted drive and run Setup.exe
- If prompted by User Account Control, click Yes
- In the Install Windows 11 window, click Next
- The setup will check your PC and show the license agreement — click Accept
- Wait for the installer to check available space
- On the Ready to install screen, make sure Keep personal files and apps is selected
- Click Install, and follow the prompts
Windows 11 will restart your device several times and guide you to the lock screen. Based on your selections, it will preserve all your files, apps, and user accounts.
For a visual guide, refer to this article:
Best wishes,
Ian | Microsoft Q&A Support Specialist