First, it's possible it's just your login session got ended, so if you haven't already tried I'd try just logging in again.
Otherwise there might also be more going on that's not related to the main/secondary menu because it looks like you have something customized, but you can try this directly in the database to reset. Assuming drupal 7.
update variable SET value = 'a:15:{s:11:"toggle_logo";i:1;s:11:"toggle_name";i:1;s:13:"toggle_slogan";i:1;s:24:"toggle_node_user_picture";i:1;s:27:"toggle_comment_user_picture";i:1;s:32:"toggle_comment_user_verification";i:1;s:14:"toggle_favicon";i:1;s:16:"toggle_main_menu";i:1;s:21:"toggle_secondary_menu";i:1;s:12:"default_logo";i:1;s:9:"logo_path";s:0:"";s:11:"logo_upload";s:0:"";s:15:"default_favicon";i:1;s:12:"favicon_path";s:0:"";s:14:"favicon_upload";s:0:"";}' where name='theme_seven_settings';
You might have a custom theme so the name=
part might need adjusting. You can do
SELECT * FROM variable WHERE name like '%_settings';
to see what you have.