Unfortunately, there are many reasons that the editor could be missing or hidden, from your hosting service locking down certain aspects of WordPress due to security or to prevent you from losing your site, to plugins or third party content/scripts hiding specific tabs.
As it’s a WordPress issue, and not directly a result of the theme, you’ll need to troubleshoot it as described in my previous thread to determine the cause. You can try going directly to the editor using the following url and inserting your own site url at the beginning http://yoursite.com/wp-admin/theme-editor.php otherwise you’ll need to go in via ftp. There’s very little we can do to assist you if the problem isn’t theme related, we can only provide you with the necessary advice to look into with WP and find the cause.
Please bear in mind that the forum is only moderated part-time, Mon-Fri so messages sent over the weekend aren’t picked up until Monday morning.