To Enable a rewrite Module

sudo a2enmod rewrite

sudo /etc/init.d/apache2 restart

To Disable a rewrite Module

sudo a2dismod rewrite

sudo /etc/init.d/apache2 restart

Now if you want to use .htaccess working, you must set the directory permission accordingly. You have to edit /etc/apache2/sites-available/default. For this, open this file in your preferred text editor. For me, its gedit.

sudo gedit /etc/apache2/sites-available/default

Then set the permission as shown below i.e. change AllowOverride None to AllowOverride all 

<Directory /home/kahwee/projects/whatever>

  Options Indexes FollowSymLinks MultiViews

  AllowOverride all

  Order allow,deny

  allow from all

</Directory> 

sudo /etc/init.d/apache2 restart

And enjoy!