I've been trying to figure out LDAP this morning and getting everything working as Read Only with Local Groups. It's struggle, what with the instructions being on pages full of links to pages full of links to...
I seem to have it working but in the process I removed a local group I thought I didn't need and now I appear to have no admin account. Can I fix it? I can log in with my AD access but no-one with an AD login has admin rights.
Follow the instructions carefully. You need to find the right config.xml and go to the right login page, then you can make sure the admin account has admin access again. Reset the admin password again when you're done.