There are several reasons Qs are removed. #4 may apply here.
1. It is a violation of the rules - you will get an e-mail when that happens. If you want to know the reason for the violation, post "Why was this question (answer) a violation?" and add the original e-mail you got so the users can see the exact context. The experienced users here will explain it to you. There is no statute of limitations on breaking the YA rules.
2. There were zero answers when the time expired - no e-mail sent.
3. The BA was reported as a violation - no e-mail sent.
4. During voting, "No Best Answer" was chosen as the best answer - no e-mail sent.
Look in your e-mail, including the spam folder, for a violation e-mail. If not there, check your activity tab in your profile. If nothing about a violation there, then the Q was removed for one of the other reasons.
Your question(s) or answer(s) were removed from Yahoo Answers most likely because they was against the Community Guidelines or it was illegal. Yahoo Answers staff removes answers and questions that violate the Community Guidelines or are illegal at regular intervals (they have an automated program that does this), and they manually check the removals over every once in a while.
Another reason why your question(s) or answer(s) got removed is because a "troll" reported it. This happens fairly often to people, especially when they ask questions in the P&S category. Just ignore it and move on if this happens. If you know who reported the question by chance (although this is highly unlikely), block that user.
Questions are also removed after 4 days of having no answers, or if someone votes "No Best Answer" for a question of yours.
You can always appeal questions or answers that are removed in violation of the Community Guidelines within a week of their removal, although you are most likely not going to win the appeal.
Did you get a violation notice for it? If not it could transpire that the best answer and not the question was deleted. If this is the case both question and answer are removed,with no notification sent to the asker.
I hear ya... I asked a simple Tax-IRS question last night and it got deleted. I contacted YA to appeal it and they havent gotten back to me yet... People flag for no apparent reason at all...