I don't know what happened, but my administrative account no longer exists. I can't add make an admin account because you need an administrative account for that, it's the vicious cycle. I've tried everything, but every time I try and make the slightest changes to my computer it doesn't let me type an admin password, or say yes. The only option I have is to decline any changes. Is there anything that I can do or do I just need to reset my computer?

What do you mean when you say that the ‘Administrator account no longer exists’? Is the user account deleted or missing now or is the user account has changed to standard account?

When the user account control pop up comes when you make any changes, is the button ‘Yes’ to accept the changes is greyed out?

This issue could be caused due to some incorrect settings or due to some corrupt user profile files. I would suggest you to try these steps and check:

First, I would suggest you to check the user accounts and their user account level in the control panel. There will be at least one administrator account in a computer. Refer to these steps to check for the administrator account:

a) Press Windows key + X and select ‘Control panel’.
b) Click on the ‘view by’ option on the top right of control panel and change it to large icons.
c) Now, click on user accounts and this will take you to your user account settings page.
d) In the right side, check the account status of your account. (Local account, standard account or administrator account.)
e) If your account is not an administrator account, click on the ‘manage another account’ option.
f) This will show a list of accounts in the computer and the user status. Check for the administrator account.