Hello, thank you for reaching out.
You may have to enter the Administrator password on the Windows Recovery Environment Screen to continue troubleshooting.
It's the same password you might have used when setting up your Windows 10 computer for the first time. So, try using the old Microsoft account passwords you remember and see if they work.
You will be able to proceed further if you enter the password correctly. If you are unable to find the right password for the account, you will have to create a Windows 10 bootable USB installation media on a Working PC and use it to reinstall Windows.
You can use the Windows 10 Media Creation Tool to create a Bootable USB installation media drive-
https://www.microsoft.com/en-us/software-download/windows10
Once the bootable USB drive is ready, plug it into the problematic PC and install Windows.
Let me know if you still need more help.