<p>When a user account is deleted their negatively voted questions are automatically deleted&mdash;even if they've got upvoted answers. There's a (currently open) feature request to change this: <a href="https://meta.stackexchange.com/questions/199860/a-question-should-not-be-deleted-by-the-user-deletion-algorithm-if-it-has-upvote">A question should not be deleted by the user deletion algorithm if it has upvoted answers</a>. But it's just an ordinary deletion: if you can see the deleted question (you need the 'Access to Moderator Tools' privilege), then you can vote to undelete it. For now, at least, it's best to alert a diamond moderator, who'll be able to quickly find &amp; undelete all the questions with upvoted answers.</p>
