How do Irepair my navigation menu? I deleted it by mistake

I am getting a error ox19
and an error 404 at the home menu drop down
This is driving me crazy I tried to add some pages to the and the navigation menu got all messed up because I added more tabs than the row of tabs could handle and they overlapped and I could not delete them. I ended up deleting the entire navigation bar and now I can not get it back.