Front page works; the rest returns "URL not found"
Note: This answer tells you how I fixed it in Ubuntu. I don't know about other operating systems, but you might wanna look up if
  mod_rewrite exits there too. If yes, you probably need to enable it
  there too.


I had that happen to me. I fixed it by enabling mod_rewrite.

In your terminal, type:

sudo a2enmod rewrite




sudo service apache2 restart