I asked a question on Stack Overflow, and a user named Molecular Man
answered it correctly. I don't know why, but he just deleted his post. I just @ notified him in a comment to ask him why he deleted his post. but I have not had a reply.
I just want to know whether the user has been notified of my comment or not? (I am just curious about it, because there is no response from that user)
@
works only in comments where the pinged user has posted comment as well, or had activity in the post itself (e.g. edit, vote to close etc). You'll have to post comment on one of his old posts asking him why he deleted his answer, then remember to delete your comment shortly if he doesn't respond.