Locked out of Windows 10 due to a non-microsoft account

Every time I try to log in to my computer, I am given the error 'We can't sign in to your account' and am sent to a temporary profile which obviously means I cannot access my files or create new ones.

The computer recently asked me to enter new account details on my profile so I added my work email which is NOT a microsoft account.
I think the problem is that as I try to sign in to the computer, microsoft is searching for a microsoft email and not finding one so is saying that it just can't sign in.
I have managed to find and copy all of my files from my account by creating another admin user and retrieving them this way (which I don't think should be possible as it seems very unsafe but whatever) but I would rather not just create a new user and delete the older user as all my programmes, emails, settings etc are still in the old account.
I have tried editing the registry, adding new profiles, and changing various settings but essentially what I need to do is change the email address associated with that user without being logged in to that user - is this possible??? I'm going insane with this and just keep going in circles!!

Welcome to the forum. Simple answer is to register the email with Ms then it's a ms account it doesn't have to be normal an email can be registered with ms

Thanks!
Apparently it already is a microsoft account (I didn't realise the guy who set up the pc had registered it) so now I really don't know.

Have you tried using the work email address and password to log into Windows?