Missing admin accounts on Mac: FIX

Shut down the computer if it is on.
Press the power button to start the computer.
Immediately press and hold the Command (Apple) key and the "s" key for single-user mode.
Type "mount -uw /" and press return.
Type "passwd" and press return.
 Enter new password (this will be for the root user account) and press return.
Type "reboot" and press return.
Enter Account settings and when prompted for administrator account and password, use the user name root and the password you just setup
Check box for you standard account to administrate box
 If all goes well you are admin again.

Then log in as Root:

dscl . -create /Groups/admin
dscl . -create /Groups/admin RealName Administrators
dscl . -create /Groups/admin PrimaryGroupID 80
dscl . -create /Groups/admin Password [password]
dscl . -create /Groups/admin GroupMembership root

Original post:  http://macosx.com/forums/howto-faqs/299801-howto-fix-user-lost-administrator-privileges.html

Convert plist to xml

plutil -convert xml1 your_file.plist

To convert an XML .plist file to binary for use: 

plutil -convert binary1 your_file.plist

Remove an ODM from the command line

To remove an Open Directory Master first delete the LDAP entries in Directory Services and then open the Terminal and type:


sudo slapconfig -destroyldapserver

It will take a while to complete.  After it has finished you should be able to remove the Opendirectory and DNS services from Server Manager (restart will be required).