Solution 1
Delete NGC folder and add a new PIN code

Go to C:\Windows\ServiceProfiles\LocalService\AppData\Local\Microsoft
In NGC folder delete all the files. To do so you must be logged as Administrator.
delete the temp folder within the NGC folder
Now go to Settings > Accounts > Sign-in Options.
Click Add a PIN and add a new PIN code for your account.

PIN login should be working again.

Solution 2:
Try to switch to local account, and the add a PIN code.
Here are the steps::

Go to Settings > Accounts and locate your account.
Click Sign in with a Local Account instead.
Follow the instructions to set up a local account.
Sign out and sign in with your local account.
Now add a PIN code.
After you've added your PIN code you need to locate your account under the Accounts section in Settings.
Choose Sign in with a Microsoft Account instead.

PIN login should be working on your account 


If you run into permissions issues:


Your case might fall into two scenario: Either you are not able to log-on into the Administrative account at all or the other case would be that you are able to log-in into your administrator account, but when you are trying to access any file using that administrator account then you are given the message as 'Access Denied'. Don't worry, if yours' is the second case, then you would be able to access all your files similar to the time before reinstalling Windows.

If the first case is true where you cannot login to any of your administrator account, then you need to reinstall windows from scratch.

If the second case is true, where you are able to log-in to your administrator account, but you are denied the permission to access that item, you can refer to this section to take control of your PCs files:

1.) Move to the location where your files are stored in your PC for which you are given the message as 'Access Denied' an select any file orr folder.

2.) Now, when right click that file,  select properties and move to security tab, then click on advanced button at the bottom  - another windows will open with all the tabs on it.

3.) Firstly click on permissions tab -> click continue (if permission is asked then click on continue) -> move to Add -> Advanced -> click Find Now -> select your Administrator User Name from the drop-down list & then click O.K. twice.

4.) An another window will open. Just click on allow button (for all) and click O.K twice.

5.) then Click on the owner tab and by clicking on the edit tab change the owner to 'XYZ' (- this is your account name with administrative rights) -> click O.K twice (or thrice) to move close all the properties box.






Reference: https://answers.microsoft.com/en-us/windows/forum/all/unable-to-change-pin-for-sign-in/64919f1b-3ac4-4bf7-852f-abdb99b905a0



Reference: https://answers.microsoft.com/en-us/windows/forum/all/im-administrator-but-am-getting-denied-access-to/3c228c71-7a64-4cf0-bf53-5851d0132f10