Yesterday ($8$ hours ago) there was a problem asking to find the residue of $\exp (\csc(1/z))$ at each of its singularity. I answered that problem and then today morning, I thought to edit my answer by adding more details. Now I cannot find that problem with my answer which took me about $30$ minutes to solve. This is the first time that I experienced something like this. Is there an this that I can do regarding this?
For the current case, the user that had asked the question self-deleted the question. I undid this and told the user that this should not be done. (It was a new user; some believe in error that this is the intended way to use the site or in any case do not see the problem with it.)
For the future, you can see your deleted recent answers on your profile page, follow the relevant link on the end of your answers-tab. For detailed instructions see How to see my answer to a question that was deleted
In this way you can usually find out what happened. Even as a user with less than 10k points, you should be able to see your answer and the question, which typically will give an indication what happened.
In case of self-deletions for no apparent reasons or other circumstances that warrant undeletion, flag the post for moderator attention (flag, 'other') and explain that this is what happened. It typically will be undeleted, or in unusual cases we can reply why it will not be undeleted in response to the flag.