I use Ubuntu Studio 24.04.1 LTS.
Yesterday I wanted to test some changes in my main account (main administer user). Of course, the system asked my superuser password. I wrote it. BUT... The system refuses to let me in.
Of course, I tested the password is right spelling. That is not the problem.
The problem is my account, my main account, that was as administrator account, not anymore!!! Today I am not an administrator, I don't know why!!!
I can see this each time I open a Terminal and I write "sudo". The system tells me: the user isn't into the "sudoers" file. ???
How can I recover the status of administrator?
How can I add my main account into the "sudoers" groups?
What can I do? ???