You will need access to the cpanel of your webhosting account ( phpMyAdmin ) and know how to generate and use MD5 hashes. Can you do this ?
If you are using Jomla 1.5: 1. Open the database using phpMyAdmin or database explorer and select the table, jos_users . (replace jos_ with your own table prefix if this is different than the default). 2. Select the record for the administrator account - by default this is user 62. 3. Copy and paste the MD5 # below and save the changes 21232f297a57a5a743894a0e4a801fc3 5. Logon to the back end http://yoursitedomain.com/administrator using the username admin and the password admin in the login box. 6. Select the user you have just logged in with using this password and username and change the password for the user to something else. This is extremely important otherwise your website might get hacked. 7. Check all is ok with Front-end access by opening your site http://yourdomainname.com and logging in using the username admin and the new password you have set it in the back end.