Lost Navigation on twentyeleven

Hello all. I’ve posted this in here as well as in troubleshooting as wasn’t sure which it most applies to..Hope that’s not bad form..I have a really odd problem that I cannot for the life of me figure out.
I’m using a child of twentyeleven, HERE.
Everything was going according to plan. I installed a plug in to send forms to database (Contact Form DB) that didn’t work. I de-activated it whilst trying to find a work around (this isn’t the problem I’m reporting though) and all of a sudden, I have no navigation. I hover over the links and I can see the links are there, but the only pages that work are for the member area when logged in, otherwise they all route back to the home page.

What on earth has happened?
Please please someone say this is a simple problem…