I can't become an a administrator on my Win 10 laptop

Question

I have an Asus K73S laptop with Windows 10 Home v.1809 (personal computer at home). I never created a user account or password on it. Windows apparently defaulted to a generic user account named User (located under the User directory as C:\User\User).

I am unable to do anything that requires elevated privileges. Any attempt to launch a program that requires elevated privileges, or to launch an elevated command prompt, produces a dialog window asking for the administrator username and password, which doesn't work.

I researched how to get administrator privileges and found this article at Windows Central: How to change a Windows 10 user account type and why. It covers five approaches, which it describes as virtually every method available:

1. How to change user account type using Settings
2. How to change user account type using Control Panel
3. How to change user account type using User Accounts
4. How to change user account type using Command Prompt
5. How to change user account type using PowerShell

I tried followed every option.

1. I don't have the "Change account type" button described in the article.
2. The same.
3. A window appeared asking me to enter a username and password as an administrator, which doesn't work.
4. The same as #3.
5. The same as #3.

I'm not an expert,can someone guide me to solve this problem? Please,suggest any diagnostic that might be helpful.

Edit: This has been marked as a duplicate of How to get rights of admin after I disabled all admin accounts in my computer. That question does contain some methods not covered in the article (so apparently, the article was wrong about it covering every method available).

QGravity's answer was covered in the article. Norbert Willhelm's answer re-enables a user account of a member of the Administrator group, which doesn't apply here.

The accepted answer may apply here, but I should clarify that by "not an expert", I mean I am a computer user and have almost no technical familiarity. I also use Google Translate to converse here in English. The accepted answer assumes a certain level of knowledge and familiarity, which I do not have. While it's possible that this would be a solution, it requires meddling with things that seem unsafe for a total novice.