@tim and @westernwoman if you installed wordpress in a subdirectory and moved index.php in root directory (because of changing your url from domain.com/wordpress to domain.com) probably you forget that you should just copy index.php from subdirectory to root (i think you moved that). now if you copy your index.php and httaccess from root to subdirectory which wordpress is there problem would be solved.
dont forget to edit index.php
