Can I use WordPress for Urdu Language? I want entire site to be toggled-translated in Urdu Language with one click... Is it possible to do it with some plugin or do i have to write manual codes for every component?
WordPress is community translated. For a good number of languages, the translation is relatively complete and follows high quality standards.
The codex page on WordPress in your language reports:
So in essence: No, WP is not entirely translated to Urdu yet. You could contribute though and push things forward, if you cared.
WP uses gettext, so the translation process itself is pretty straightforward. See I18n for WordPress Developers, if you want to find out more.