If you are talking about the nav links just under the tabs that is always there.
If you couldnt see it then its possible one of your Admins/Global mods edited the css and changed the font color and it blended into the background.
If something is changed on your forum by one of your Admins I would ask them what they changed and where so that you know. (Also as we have told you many many times: stop giving others access to do these things)