In general to undelete the original, possibly making an edit, seems the better option. (Note however that revisions are usually preserved, so if some confidential material really needs to be removed this might not be an option, at least not without some extra step.)

While it can be difficult to keep access to deleted content, almost all deletions of posts are only soft-deletions and can be undone.

To keep track of a question, it suffices to bookmark the URL of the question; it can be a good idea to do so before self-deleting something one might need later.

In case of difficulty, our moderators, which have better access to deleted content, are likely willing to help.