It's happened a few times that I recall writing an answer on a topic but can't find it later. I think it happens when the question was deleted -- for example, if the answer has score 0 and the user deleted the question, or if the answer had 0 score and the question had negative score and the Roomba removed it.
(Although my memory could be playing tricks, such as when I'm misremembering -- sometimes I write part of an answer, become dissatisfied with it, and discard the draft. But there's simply no way to recover the content in that scenario.)
Is there an easy way for me to find these answers? I have the privilege that lets me view deleted content, but only if I happen to find a link to it -- I'm not aware of a mechanism that lets me search or readily list things that are deleted. (Except in the case that I voted to delete something, in which case I can see it in the Delete tab under Votes.)