Last week I started playing around with LAMP Ubuntu and I didnt have any issues. Today some code wasn’t working so I tried running this in index.php:
<?php phpinfo(); ?>
This doesn’t work when I connect to localhost in my browser, but it works in testphp.php at localhost/testphp.php
Try renaming the file to index.php
If you mean that code doesn’t get executed when you access http://localhost/, then you should try to add
DirectoryIndex index.html index.php
to your apache’s conf file.