cangpo

Probably it was “bad” cache

You need to recover your database from old site to new

I have one idea!! Try to reload page, and save your widgets ??

deleted

Copy from nav-menu-template.php walker code, that start with
“class Walker_Nav_Menu extends Walker {…” to your function.php, and rename it:), like this one: Walker_Nav_Menu_dropcornermenu

Change:
$output .= "\n$indent<ul class=\"sub-menu\">\n";
to:
$output .= "\n$indent<div class=\"drop\"><ul class=\"sub-menu\">\n";

and also:
$output .= "$indent</ul>\n";
to:

$output .= "$indent</ul><div class=\"bottom\"><div class=\"box-center\"></div><div class=\"box-right\"></div></div></div>\n";

After all, just call your nav_menu

<?php
$walker_mymenu = new Walker_Nav_Menu_dropcornermenu ();
wp_nav_menu( array ( 'walker' => $walker_mymenu  ) ); ?>