Can't access site, lost password and username

There is a possibility, yes, that you reset the password and user email through your database access.

Are you familiar with PhpMyAdmin ?

You can check this guide for resetting your password : http://codex.wordpress.org/Resetting_Your_Password#Through_phpMyAdmin

You could also use this to update (in the wp_users table) the email addy associated to your username. If there are only few users on your blog, just open your blog’s database in phpmyadmin, move to the wp_posts table, scroll a bit ,you should see the mention of an email addy, the old obsolete one. Simply replace it with your current addy, hit Enter (or, what, Execute, I don’t remember) and it’s saved.