Ok, there's the address bar and the search box. Are you talking about a previous design of the address bar or the search box? If you're talking about the search box, it's still there (either addable to the toolbar or there by default, I don't remember). If it's the address bar, I don't know exactly what functionality you're looking for.
@Ketchup - eh?
I'm referring to the search bar (or box, as you seem to prefer) as seen here:
It was replaced in Firefox 30-something with the following, a
significantly worse version:
For a while, you could get the original by setting 'browser.search.showOneOffButtons' to false in about:config. They removed that option in.. early 40-something, though addons could still bring back similar functionality, and then Firefox Quantum removed even that possibility. The Australis interface was bad enough, but removing the search bar is just too much.
And as for the address bar, if I meant address bar I would have said it.