how to retrieve lost Super Admin permissions

I have two users. One is administrator. But user name is different .Say “Bob”. There is no user in the username “admin”. “Bob” is the administrator.when “Bob” tried to install new themes and new plugins, I got this message. “Sorry, but you do not have the correct permissions to install the Contact Form 7, Regenerate Thumbnails, Responsive Lightbox and WP-PageNavi plugins. Contact the administrator of this site for help on getting the plugins installed.” I don’t know which administrator should I contact. I checked database. It seems OK. Could any one help me to solve this please..