Additionally, Windows 10 might force your computer to restart automatically after installing updates. Try to disable automatic reboot:

Open the Local Group Policy Editor.
Browse to: Computer...

Could you see which module (or file) caused your computer to crash?
Try to uninstall the softwares you installed recently, or restore Windows to the latest backup point.

When my computer wakes up from sleep, it goes directly to the login screen, without showing the lock screen. I think you can consider disabling the lock screen:
Lock Screen - Enable or Disable in...

Could you see your account icon on the login screen? If there is no account icon, it's possible that you're stuck at the lock screen, not the login screen.

It might be caused by a driver you installed recently. You can use the freeware BlueScreenView to open the .dmp file for analyzing the possible causes: Blue screen of death (STOP error) information...

Open File Explorer and go to C:\Windows\Minidump. Look for any .dmp file that was created almost at the time when your PC restarted. If you can find one, it indicates that your computer experienced a...

Did you changed the owner of the C:\ drive or all its subfolder? By default, the owner is TrustedInstaller and make sure you change it back.

You might need to replace {default} with your own identity. Type bcdedit and press Enter, it will list all your identities.

Boot your computer from Windows installation disc or Windows RE. Open up a command prompt and type the following to turn off safe mode:

bcdedit /deletevalue {default} safeboot

After running the...

Just a few minutes ago I got the adding PIN to work. My fix is start the service named "Distributed Transaction Coordinator", re-open the Settings and I can then add PIN successfully.

That way allows you to enable the hidden & built-in administrator account. After logging in as administrator, you can change your own local account to administrator.

See option 4:
Administrator account - Enable or Disable in Windows 10 - Windows 10 Forums

I have the same problem. Windows 10 build version is 10.0.14393 and I've installed all updates. I use a local account. When clicking "Add PIN" in the Settings screen, it lets me to type local user...