Hello,
Regarding the PIN, I have a few questions here:
- How do you usually sign in to your PC? Do you use a Windows Hello PIN? Have you forgotten your PIN, or is the option to enter it unavailable?
- What is the exact error message displayed on the Windows sign-in screen?
- Do you have another sign-in option, such as your Microsoft account password, that you can use to access your device?
Based on your description, it also appears that you are having trouble verifying your identity because you no longer have access to your old Phone number.
If you no longer have any other verification methods besides the recovery Phone number, you will have to replace it.
That is, on the Verify Your Identity screen, select 'I don't have any of these' and follow the prompts to replace the Security Information.
Note:
If you remove all of your previous security information and replace it with something new, your account will be put into a restricted state for 30 days.