Hello, I'm Greg, 10 years awarded MVP, here to help you.
Besides in Settings > Accounts > Access Work & School, check if there are any accounts in Settings > Accounts > Email and Other Accounts or a work or school account are still in Windows Mail App > Settings > Manage Accounts.
If nothing is left of the Work or School Accounts then uninstall any 3rd party antivirus and use built-in Defender.
If that isn't causing it then your account is corrupted. Test a new account by creating a new Local Admin account in Settings > Accounts > Family & Other People > Other, as shown here:
https://www.isumsoft.com/windows-10/3-ways-to-c...
Sign into the new account, test if the problem persists, if not then move your files over, test that all programs work or else reinstall them, then when ready delete the old account in the same place.
You can then change it to your Microsoft account if desired:
https://www.tenforums.com/tutorials/5375-switch...
If all that remains is the PIN refusal, you can also try Here's here how to reset the PIN in Windows 10 when it will not work from Settings > Accounts > Sign In Options:
Open Windows File Explorer using the file folder icon on your task bar.
Tick the box in File Explorer View tab to Show Hidden Files.
Browse to C:\Windows\ServiceProfiles\LocalService\AppData\Local\Microsoft\Ngc
Delete or rename to Ngc.old this folder to reset the PIN.
**You may need to first take ownership of the folder: https://www.tenforums.com/tutorials/3841-add-ta...
Once you delete or rename the folder it will recreate it so you can add a PIN normally in Windows Settings > Accounts > Sign-In Options. You may need to restart the PC first.
For any unexpected problems see tutorials covering all possible problems here:
https://www.askvg.com/fix-unable-to-add-and-use...
https://www.lifewire.com/remove-pin-from-window...
Based on the results you post back I may have other suggestions if necessary.
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