If you lost your Joomla admin password and you have direct access to the database, or via PhpMyAdmin, you can enter the following SQL sentences:

INSERT INTO `jos_users` VALUES (62, ‘Administrator’, ‘admin’, ‘your-email@email.com’, ‘21232f297a57a5a743894a0e4a801fc3′, ‘Super Administrator’, 0, 1, 25, ‘2005-09-28 00:00:00′, ‘2005-09-28 00:00:00′, ”, ”);
INSERT INTO `jos_core_acl_aro` VALUES (10,’users’,'62′,0,’Administrator’,0);
INSERT INTO `jos_core_acl_groups_aro_map` VALUES (25,”,10);

If this causes an error, you probably have to delete the db rows that have the same primary key of those you want to insert.