Some of my friends ask me several times about how to reset admin password of Mambo CMS. They forgot the admin password, and want to reset it :). The trick is very simple, but it needs proper access to PHPMyAdmin of the Mambo database. Fire up PHPMyAdmin and navigate to mos_users table.
The next step is deleting the user with SuperUser role in mos_users table. Then you need to insert new Admin user with SuperUser permission. But it can not do to the table directly, because Mambo stores the password in encrypted field :D.
Don’t worry, open the mambo.sql file that contains Mambo database script. Search for the script that doing INSERT the Admin account, copy this line of INSERT statement and run it to your Mambo database. It inserts new Admin user name with default password: Admin. 
If you’re to lazy for opening and observe mambo.sql file, just run this script in your PHPMyAdmin:
INSERT INTO `mos_users` VALUES (62, 'Administrator', 'admin', 'admin@wherever', '21232f297a57a5a743894a0e4a801fc3', 'superadministrator', 0, 1, 25, '2004-06-06 00:00:00', '0000-00-00 00:00:00', '', '');
By abe on Apr 15, 2006 | Reply
nice tips..
how bout if we do not know the password of PHPMyAdmin bang?
hmm.. simple.. re-install
By MCA on Apr 16, 2006 | Reply
heheh, if you forgot phpmyadmin password, just fire up mysql command prompt and reset root mysql password to blank
By Pauline on Apr 18, 2006 | Reply
Hey! Thanks for the tip!
An even easier way to do it if you have phpMyAdmin is to just replace the encrypted password with:
21232f297a57a5a743894a0e4a801fc3
Then your new password is admin. You don’t actually have to run the sql command.
By MCA on Apr 20, 2006 | Reply
thanks pauline, it’s also doable.
but sometimes people do incorrect select to encrypted password.
By Mario on Mar 28, 2007 | Reply
I have done all of this and I have added a new user but no matter what I do I still get an error pop up message saying invalid username, password or access level. I’ve moved my mambo server to a new host and backed up the database before doing the move.. I did a new install (version 4.5.3) and then uploaded all the files (templetes, images etc) the front end works fine, but the admin section cant be access. I’ve tried both approaches with the sql string and just changing the password (Yes MD5) and nothing. If I can’t access the admin I will have no choice but to reinstall but a lot of work will be lost. Any ideas????