Here is a simple solution...

If you have locked yourself out your Mambo installation, (i.e.) lost your admin password, you should be able to reset it without issue as long as you have access to your database via phpMyAdmin, the MySQL command line utility, SQLYog or some other similar program.

Simply login to your database and run the following statement:

 

update mos_users
set password = md5('newpassword')
where username = 'admin'; 

Replace 'newpassword' with the new password you would like and replace 'admin' with whatever your admin username is. The admin username is 'admin' by default so unless you changed it this is probably still the same. Replace mos_users with the name of your user table. The '_users' part will always be the same, but if you selected a different database prefix during installation then 'mos' may differ. If you left the database prefix alone during installation then the table will in fact be 'mos_users'.

If you are not confident about using the MySQL method above, this "How To" provides other ways in which you can reset your admin password.

Sadly, you cannot recover your existing password, but the good news is - you can set a new one! Passwords are stored in the Mambo database and are encrypted using a one-way MD5 hash, which means your only option is to set a new, hashed password.

Now, how to do that.
First, you need to create a new MD5 hashed password. There are MD5 utilities available on the web which allow you to make your own hashed password.

Here are two online MD5 creators:
JavaScript MD5 - http://pajhome.org.uk/crypt/md5/
MD5er - http://www.md5er.com

Make sure you create a STRONG password, ideally 8 characters in length and nothing from the dictionary or anything that can be guessed at.

Secondly, you must edit the password field in your database. So, login to phpMyAdmin or whatever MySQL database manager your host provides. Look for the users table in your Mambo database. If you accepted the default suggestions when you installed Mambo, your user table will be called mos_user. Browse to the username that requires the password change.

If you are not comfortable with creating your own hashed password, and you use phpMyAdmin, you can enter a plain text password into the record in your database and choose the option, "MD5" from the phpMyAdmin dropdown options. phpMyAdmin automatically encrypts the plain text you entered as an MD5 hash. Save your change and exit your MySQL manager.

That's it! You should now be able to login using the new password.