User Profile Failed to Load

Hello Gals and Guys -

When I cam home yesterday and fired up my computer, I got the blue screen "User Profile Cannot Be Loaded" screen. I had this happen once before last year. I was able to log on that time and replace the user.dat file in the default profile folder, which fixed the problem, but this time I cannot log into my PC. It just thinks about it, then kicks me back to the log in prompt. If I can't log into the machine to replace user.dat file, how can I fix the problem?

I was reading profile failing to load can be related to Windows Update and for the past few months I've had an update that fails, 21H2 if I recall correctly. I select restart and update, but it only gets 30-40% of the way before it reboots again, then says it cannot complete the update and rolls it back before rebooting. I'm not sure they're related, but thought it worth mentioning. Thanks for any help.

Thanks Brink. I appreciate the help. I opened the advanced page by holding the shift key while rebooting and was able to open to get the command prompt working. When I logged in, it only showed my user account, not the admin, so I'm not sure I did that part correctly. I got to the part where I loaded the hive and entered REM_SAM into the box, but I got the error message "Cannot Load X:\\Windows\System32\Config\SAM. The process cannot access the file because it is being used by another process, so that's where I'm stuck now. Thanks again.

Thanks Brink. I do have a Windows 10 disc I burned, but my other computers consist of two Macs and a notebook running Linux, so I'm not sure how I'd make a Windows USB drive. I'm wondering if I can make a Linux Live CD and just move the file over to the right folder like I did last time? Thanks again.

Thanks Brink. Yes, once I had access, I renamed the old user.dat file from the default profile folder, then copied the one from my user folder into the default folder and it worked like a charm. I guess the good Lord helps them who helps themselves. Thanks again.