Where can I get the reason for having been banned for asking questions on Stack Overflow? I haven't found any reason for this, and I haven't yet found any Internet resource where user can be banned without any explanation, so I think such a good site like Stack Overflow has a page where I can read administrators' doings connected to me.
You keep on deleting questions you ask. That is poor practice. If you ask something, let the loop be closed and let others answer you. If you get no answer, you can always answer it yourself.
To avoid asking dupes, search well before asking.
Also, take some time and provide awesome answers.
Your case is borderline, the ban will most likely be lifted if you contribute one or 2 awesome answers, you are clearly capable of providing.