You didn't give the Drupal version. I would start with the backup for sure.
Ooops - 5.7
The admin/content/types lists the content types available for your access rights. The admin/content/types/audio would give a page to edit the attributes regarding the content type audio.
Yes, correct on both counts! The only problem is our site is broken for some reason, as noted in my last post. I did see on d.o that module incompatibilities can cause this behavior. I saw such a post anyhow.
Other modules may add tabs to the page but only if your user has access to the function provided by the tab.
After the backup I would check the access to the functions for the user. Are you user id 1 or are you using some role with rights given?
User id 1 of course.
I am anyhow in the process of updating all contrib modules to latest versions. Interestingly enough, I had to degrade admin_menu b/c the latest version actually caused a completely blank page for user id 1. The older version works fine for us.
If that fails, then I will start to disable modules one by one I guess...
Thanks!