Yesterday (about 18 hours ago) I answered this question and put some comments to my own answer. Today, I have revisited it and added three comments to someone else answers. Particularly to this one (reply to lesto's comment), to this one (with a link to my reply to lesto's comment) and to this one.
Now, all three of my comments are gone and my activity tab shows nothing about them.
I tried to refresh page many times and see it through different browsers, to prevent any chances, that something "choked" on cache or sth. No effect. I'm pretty sure, that I wrote these comments, because I'm editing my own blog in the same time and I have copied contents of these comments to by post.
Can someone verify, what has happen and reply me, why my comments were removed? Since there is not trace about them in my user's activity tab, I think, I need a help from side of site administrator or anyone else with access to internal logs.