Links in header gone

I’ve just upgraded from 1.5.x to 2.2.2. I did an incremental upgrade, so to elliminate any chances of a failure. Everything worked as expected but one thing.. In my header, I used to have all my navigation links, and somehow they’ve disappared. (i’m using the “Static Front Page” plugin and keep all my navigation in the header to keep a clean look) We used to be two administrators, and it’s the other guy, no longer reachable, who setup the initial page and made it work the way it was. I’ve been struggeling for some time now to get it back as it was, but i’m stuck… It’s just an empty space where my links should have been. Anyone have a clue whats going on, and how to fix it. (PS; I’m quite new to WordPress, so please do bear with me..)