I have found a question very similar to this, which I thought would solve my problem.
However, after changing my .htaccess file, with index.php on the end of the list, and then index.php as the only entry, I still cannot get index.php to display. Every other page works fine, but I don't know how to fix this. Thanks.

tail -f /var/log/apache2/error.log– Lars Rohrbach Nov 11 '12 at 5:52;at the end. – Lars Rohrbach Nov 11 '12 at 6:18