It probably wasn't actually banned; it's just fallen foul of AB's pathetic system.
Every evening (particularly at weekends) lots of questions appear in the 'unanswered questions' pane but, when you click on them, the page with the question on doesn't exist.
It happened a short while ago to a question (intended for the 'Road Rules' subsection) about HGV speed limits, and there have been several others like that tonight. Yesterday somebody tried at least four times to post a question about using PayPal to purchase food; the questions kept appearing in the 'unanswered questions' pane, but they never showed up in 'Food & Drink'.
I've contacted the technical team about this in the past, but they simply attributed it to people getting banned. (That's clearly absolute rubbish, since you've not been banned and I very much doubt that people posting questions about speed limits or PayPal have been banned).
I'll send the techies a link to this thread, but don't hold your breath for any improvements!
Chris