The data is stored in the database.

But have you tried opening Developer Tools in your browser and manually looking for the CSS that is causing the tabs to disappear?

The data is stored in the database.

But have you tried opening Developer Tools in your browser and manually looking for the CSS that is causing the tabs to disappear?

so maybe its' not that but that's the only thing I changed today.. old site works fine... but new site none of the menus work.. 

Look for relevant error messages in the Developer Tools >  Console of your current web browser.

Try accessing the page from a different web browser.

Those are my best suggestions off the top of my head.

Feel free to report back with any relevant information you discover.

Have you made any progress on this?