404 Not Found The requested URL was not found on this server WordPress and Ubuntu

Step 1. Edit in apache2.conf 

cd /etc/apache2
sudo gedit apache2.conf

Step 2. Here in apache2.conf change

<Directory /var/www/>
     Options Indexes FollowSymLinks
     AllowOverride None
     Require all granted
</Directory>

Step 3. to

<Directory /var/www/>
        Options Indexes FollowSymLinks
        AllowOverride All
        Require all granted
</Directory>  

done!