resetting passwords if you can't get in to the website

Give this article a read.

http://codex.wordpress.org/Resetting_Your_Password

Personally I think this is the easiest method to use.

http://codex.wordpress.org/Resetting_Your_Password#Through_FTP

If you do use that method then please make sure you have an unaltered backup copy of your theme’s functions.php file before you make changes to it.