Dumb question but with several admins on the board. Have you double checked they are indeed still admins.
No resolution to why you can't see the settings but maybe someone removed the admins from the admin group.
Goto cp>group management
on the top line is administrators to the right is a column called members. This shows how many admins there are. You can click on the number and it will show all the admins. See if everyone is there.
You can also goto cp>logs>view admin logs select a date range and see if someone was poking around in the control panel.
