Sometimes I take a look at questions over in the "related questions" area and see a puzzle from a while ago, and I was wondering what the site's policy is on answering old questions. If a puzzle hasn't been touched for multiple months, is it still okay to answer it? A lot of the time, the asker hasn't been active recently and it's possible they no longer check their SE or do so very infrequently, so wouldn't accept the answer even if it's correct (for a while at least). This would also draw attention from other people to comment/answer when the asker may no longer be active.
If we shouldn't answer these old questions, then how do we go about posing the question again? If I am asking a question, and see that it's a duplicate of an old question that was never answered, what should I do?