Are you the ONLY admin at the school? If not, then get your other admin to log in and put you back on.
If yes - then do you have access to the files on the
server (like
ftp access)? There is a desperate admin fix here which you have to put in to your Moodle folder on the server to reset everything -
it is hereIf you don't have access to the server then you are going to have to get in touch with the person who does - is that your IT guy??
PS - do you not even have "turn editing on " on your front page? Sometimes people accidentally delete the admin block and that's an easy one to get back.
When it is all sorted again, as it will be, don't worry about working on roles for your students -they don't need anything altering from the front page.
Good luck