Out of my 6 articles, one of them has the following message in the comments area which was not there in the start: "Comments for this thread are now closed."
I have done the following 3 options but non of them worked:
1 - "In the Post Edit go to Screen Options (top menu) and mark the Discussion and Comments boxes.
Then, go down the page and mark the "Allow Comments"."
2 - I disabled all the plugins to find out if any of the plugins is conflicting with disqus and left only disqus and I was having the same problem and when I disabled disqus plugin then I was able to post comments.
3 - I unchecked "Automatically close comments on articles older than this number of days" and I also increased the number of days to 999 when it was in checked stat but didn't work.
Any help other then the above steps will be appreciated