Found the culprit. I've added below code in qa-theme.php file to show google adsense after all answers. It's displaying google adsense ads but hiding all answers then. I removed the below code and all answers are back again.
//ad after all answers, just before related questions
//Put your ad code in between below brackets
Google adsense code
Any way to correct this code or any other way to add Google adsense code after all answers?
Thanks in advance.