If you want to get question URL than use qa_q_path() or qa_q_path_html()
qa_q_path($questionid, $title, $absolute, $showtype, $showid)
If something else than please mention what you are trying to achieve so we can try to help in that way.
For qa_path or qa_path_html you need to set $request parameter with the page you want to load. For example if you want to load Questions page with Sort by Answers than you would use this
<?php qa_path('questions', array('sort' => 'answers')); ?>
So here questions is your page and sort by answers is a parameter and url will be as below
I hope this would be helpful to you. :)