The best thing is that you can enable or disable the in-built Administrator account using Command Prompt instance in Terminal. However, if you already have the account enabled, you can use it ...

2] Activate Administrator account through Command Prompt Try activating the administrator account using the command prompt and see if it is able to fix the problem.

Open Command Prompt or PowerShell as Administrator: Follow the same steps as above to open Command Prompt or PowerShell with administrator privileges. Disable the Super Administrator Account: ...