You can remove your custom-edit from your .htaccess
file and edit the permalinks
settings (i.e. revert to default), save the changes. This way Wordpress
will be forced to re-generate it (if it has any errors) and everything should work.
This .htaccess
file should be located in root
of your Wordpress
installation (you may have other .htaccess
files in sub-folders as well).