Clear Cache without logging in
i. If you have drush installed (http://drupal.org/project/drush) — if you don't have it, think about that next time :), open up the console (WIN+R) in Windows or Ctrl+Alt+T in Linux point to your site folder (e.g. cd /www/mydrupalsite/ and type:

 $ drush cc all


from the command line.

ii. Another method is to log into your phpmyadmin select your cache_ tables and flush/empty  them.