I wanted to purge the LAMP server I installed on the machine. So I used
apt-get purge apache2
apt-get purge php5-*
apt-get purge mysql-server

Then I still found many files related to the LAMP server on my filesystem.
Then I used a command to somehow remove the which was the biggest mistake I made:

sudo rm -r /etc/apache2
sudo rm -r `locate mysql`
sudo rm -r `php`
sudo rm -r `apache`

The last 4 commands were really stupid and dangerous.

Now I cannot get the ubuntu login screen. After selecting ubuntu from grub, I get an error sceen saying:

Invalid command Order in apache.conf
*starting likewise service manager : lwsmd [ fail]
* starting likewise open service [fail]
*starting web server apache2 [fail]

I am able to drop to root shel from recovery mode but as the network is not configured, I am not able to connect to any remote servers or repositories.