Depending on your reputation, you can edit the answer / comments of others. It's usually not recommended to change the context of the question or the answer but you could. Those update will be reviewed by other if needed. As for the correct answer, you can always upvote the answer you feel is the correct one, which is kind of a community way of selecting the correct answer.
That is exactly what stackoverflow is supposed to be. It's not there to answer your question about "why is my IF statement not working", it's there to be a resource for all developers. How is a question about your specific problem gonna helps anyone ? If you haven't, take the time to read the "how to ask" section, it describes what kind of questions are acceptable and what kind are not.
There is, obviously, some proper questions that should not have been deleted, but most of them are not suited for the site, as they don't bring anything to the rest of the community.