Tags menu -- Disappeared in the side menu....need to restore back

Hi All, I don’t know , if I accidently did anything where I don’t see “All tags” side menu to view all the tags. Also optional tags doesn’t show the tags…but when I go to my site with this url…www.example.com/tags. I see few tags listed… I want to have all tags and “Add tags” option in side menu…How to enable them as shown in this screen shot…Is their any configuration in Admin , to do so…