1.
You have to go to /etc/apache2/apache2.conf.You have to edit that one(you should have root permission).
Change directory text like this
<Directory /var/www/>
Options Indexes FollowSymLinks
AllowOverride All
Require all granted
</Directory>
2.
sudo a2enconf httpd
3.
Restart Apache2sudo service apache2 restartDone!
or
sudo service apache2 reload