Troubleshooting a broken website takes a lot of time at this end – We’re a one man team and not only do I run my own troop, but I have plenty of other responsibilities as well as a full time job, so if you’re knowledgeable you too can become your own website debugger.  You may need shell, ftp or database.  I can happily grant you access to these services quite quickly compared to fixing any mistakes!

White screen of death (when upgrading one of your plugins breaks)

http://perishablepress.com/quickly-disable-or-enable-all-wordpress-plugins-via-the-database/

Backing up your site from the command line:

http://www.cyberciti.biz/faq/how-do-i-compress-a-whole-linux-or-unix-directory/

Backing up your database from phpmyadmin:

http://codex.wordpress.org/Backing_Up_Your_Database

Changed the site URL?

http://codex.wordpress.org/Changing_The_Site_URL (I suggest changing the database option)