In case you find the password Administrator changed, you can follow the instructions which explain how to redefine it manually using MySQL Panel.
Alternatively the file "change_pwd.php" is available here enclosed, which allows to automate such a process.
USE OF THE FILE change_pwd.php:
1) Copy the file in the root of your Joomla by Ftp and rename the file as .php
2) Remind to the Url of the file in the format: http://urlofjoomla/change_pwd.php
3) Enter a new Password
Once ended the process, the password will have been already updated in the MySQL database.