admin block deleted- Can't get it back :-(

I inadvertedly deleted the admin block. Now I cannot manage my site anymore!
I tried the "add block" menu but the admin block isn't listed
I went to admin/blocks.php but isn't listed there either
I looked to the mdl_role_assignment table and roleid is 1 (manager) in all the instances of my userid

What also can I try?
This is on Moodle 2.3.2+ (Build: 20121014). Theme is sky_high

I see that from one of the courses I can still get to the add-courses page (home>admin>courses>add/modify course) from the "courses" link of the breadcrumb (in the other courses it is greyed out), but the "admin" and "courses" links on the breadcrumb there are greyed out.

pretty desperate...

thanks

Piersante