Accounts Disabled

Did you change the "short name" of your user account? You should never have to change this part and you should never do it without having a full verified working backup since it can be difficult for people to fix it. Here is the official Apple document on the subject. If you have no other admin accounts available, then you can try booting into Recovery Mode or Internet Recovery Mode to access the Terminal app to rename the user folder to match the short name on the account.

https://support.apple.com/en-us/HT201548

If you changed something besides the short name or the full name, then please post exactly what you did and what instructions you were following.

Hi there, Help_Need!

Thanks for reaching out to the Apple Support Communities! It sounds like you are seeing a message that your account has been disabled after changing your username. I recommend you check out this article If your Apple ID is locked or disabled. This article will give you the steps you need to take for issues with your account being disabled.

If you are unable to enable your account, I would recommend checking out this link to Contact Support. This link will get you in touch with Apple directly for the next steps you’ll need to take. 

Have a great day!