A problem with the yet unreleased versions of Drupal 6 is that in some cases Drupal all of a sudden seems to lose all of its paths. In my case it happened when working on a port of an OSInet module from the Drupal 4.7 to Drupal 6 API.
A symptom of the problem can be seen by checking the
menu_router table and finding it to be empty, although it should contain the default site navigation.
Before reinstalling, a
quick hack/fix can return the site to a better behaviour: since Drupal knows how to install itself, how about asking it to regenerate the
menu_router table ? Luckily, there's a function which does just that: menu_rebuild.
So just edit
index.php at the root of your Drupal install, just like this:
menu_rebuild(); // use just once
die(); // use just once
$return = menu_execute_active_handler();
Now invoke any page on the site, just once, then remove the two added lines, and your menu should return to normal.