The apache2 version that was published when the Ubuntu 14.04 release was made is 2.4.7 and starting with this version it seems that, for security reasons, the new root directory for the server is:
/var/www/html
So, from now on, this is where you must place the files for your (local) website. You should not have this problem again with the future updates.
Anyway, if you want to change this directory with another one, you have to modify (as root) the following line from /etc/apache2/sites-available/000-default.conf
file (sudo nano /etc/apache2/sites-available/000-default.conf
):
DocumentRoot /var/www/html
to
DocumentRoot /path/to/another/directory
After this, for the new changes to take effect, you have to restart the apache server using the following command:
sudo service apache2 restart