There was an answer with a downvote. After a fruitless discussion with the author I also downvoted the answer. Today I found the answer but the downvotes and all the comments disappeared. There were also some changes in the answer so I looked in its history to check if I find a version with the original text. This was the case and I also found out that the answer was deleted and undeleted. Did this deletion and undeletion of an answer remove the comments and the votes? If so, is it a respectable behavior to do this?
There is a deleted answer by the same user with 2 upvotes and 2 downvotes. Two your comments are below that answer.
After you reach 10k reputation, you will be able to view deleted posts. (And also moderators and the OP can see deleted post, regardless of their reputation.)
Even below that reputation, you should probably see on your reputation tab that an answer you downvoted was removed - since you get back the reputation deducted by the downvote. (Make sure you have checked the option show removed posts. IIRC the reputation changes related to downvotes are shown only to you - other users don't see them when they look at your reputation tab.)