Thank you Steven for being caring.
I think the problem has solved out. I deactivated the plugin to see. Problem solved. Then i activated it again to see. Nothing happened. Problem solved.
However, what i did that might resolved the issue was this (which you had also indicated to check if any other plugin is messing up):
I went to wordpress Setting > General and …
I was asked to make sure that the Site Adress and WordPress Address must be the same. They both were same.
There is a plugin I had installed ‘WP Force SSL’ which says to put ‘https’ (not http) before the addresses. I did. This might has resolved the issue.
This is for now. Thanks.