Ok, thank you for your help. I understood the problem but now I got into a new big one. The db user I created was inexplicable gone (so no users were left). So I created a new one but I mistook the name so I try to delete it. I am sure 100% I click on the delete user button at the bottom of the MySql admin page, in the current users box. Well, after the confirmation, the entire Database was removed!!! And I tried to create a new one with the same name but the system told me that the name was already taken! I refreshed the page several times but nothing changed. It was strange so I waited a minute and I refreshed the admin page again. This time the DB was come back but sadly empty. I think that I could re-create the DB in spite of the error message. Anyway from PHP myadmin I failed to populate the DB through sql, because in spite of the total emptyness of the db it was still storing the table! (they appeared on query tab!). What I did was I deleted everything and I did it again.
This time a db user was created automatically by default (because is the same name of the old one I tried to delete, I think it was never deleted). So, to prevent the same situation as before, I created a new user and then I deleted the wrong one.
Now everything is fine.
I just wrote to you all this story just to let you know for maintenance purpose.
Thank you.