Unable to log onto main user account.

I am suddenly unable to log onto my main user account because it has just seemingly been denying all logging-in attempts. It randomly disappeared from the login screen and for some reason it wont login with any users, the only user it displays is the most recently logged in user and other users.
Other users doesn't seem to work no matter how theoretically correct attempts I input into it. I've tried changing the password and username via the control panel. I've tried messing around with the login screen settings in the group policy manager, but nothing is working.
This user contains a bunch of important data that I can only access on said account, and having to get rid of it will get rid of a ton of data, mainly relating to web and application info. How in the hell am I supposed to fix this???

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Another thing, somehow logging into another user account that isnt my main one or the administrator account causes all of the icons to break, and causes control panel to stop working, but specifically only for that account.

I tried this and it made everything even worse. I can't even access windows at all now in normal or safe mode.

Apparently the reason why I couldn't get to the logon screen is that sfc/scannow somehow deleted winlogon and authui?? Adding them back allowed me to get to the logon screen again but I can't access the other account still.

I still haven't been able to log in to the user account, however I'm able to access all of my programs.
The disk is fine, and the windows 10 install I use boots perfectly fine.