There is yet another way ...
In config.php file enter a line to grant user ID's site admin roles.
$CFG->siteadmins="2,#";
where 2,# are known user ID's. User ID 1 is guest (don't use that one here), User ID 2 is normally the original user created when the Moodle was first installed. Admin level users may have added many moons after install so those users will not be sequential but spread out. In your case, your user ID might be something like 4420, as an example.
So, using any account where you can login as that user, login and look at the user ID which will display in the URL line to some resources in Moodle (like Profile).
So Bob Jones - bjones - is a known account and can authenticate (login) to Moodle. ID is 354.
In the config line above replace # with 354. Save the config file. Login as bjones.
Go to the admin user - the one you desire to use as the admin - edit profile, change password. Don't worry about getting notification. Write it down. ;)
Logout from bjones.
Try the admin account again.
If successfull, re-edit your config.php file and comment out the siteadmins line you added by placing // in front of it. No need to reboot/restart anything. While there, might add that other user account to the siteadmin config line.
bjones is no longer site admin level and you should be able to now login with the admin account.
HINT: create another account using info you know. Set that user as admin level. Use it only as a 'backup' to accessing the Moodle as admin level in case of other hickups. This is not the normal process so any future admins should be added via the normal Moodle UI as an admin level user.
'spirit of sharing', Ken
