Language switcher in the same page (do not redirect in the homepage after switch)

Problem:

I have two languages installed. When I am in a page, for example in contact page, and then I press second language flag, it redirects me on the home page.

Solution:

You can do that with "Menu Item Association":
Extensions > Plug-in Manager > "System – Language Filter" > Menu associations: Yes.
Then in the Menu Manager use "Association" to associate menu items with menu items in other language(s).

source: http://forum.joomla.org/viewtopic.php?f=617&t=773779