I have just started using ubuntu 12,04, there i have a problem with libreoffice. it does not show some of the characters of the urdu langage, instead boxex appear. what should i do?
Make sure you have fonts installed that cover these characters, and select one of the fonts for document formatting.
Right – as @cloph said, you’ll need appropriate fonts installed.
Here’s a page about enabling Urdu support: http://blog-on-technology.siddiq.me/2012/05/type-urdu-in-ubuntu.html