How can I tell if I am short-listed for Phd position? I applied for a phd position whose application deadline was 24th March. The project head consistently provided feedback on my project proposal and even invited me to his office to discuss my proposal. At the end of April I contacted my potential mentor asking when to expect the results, 
he replied that this week the commission will hand over its list to head of department. He will do interviews with possible candidates, I guess next week. Thereafter the appointment committee will make the final decision.'

Until now I have received no further information from the institution nor was any list published at the institute website. I contacted recently the institution through mail asking whether I am selected or not but got no reply.

So, considering what my potential mentor said, does his words mean that I am not selected for the position? Or should I wait? I am confused about what to do next, in order to know if I am selected or not.
You would more probably learn early of a rejection than an acceptance. I'd say you are still in the running. Unless you have another option with a deadline, I suggest you wait a bit. 

It may take a while after decisions are made for candidates to hear due to nothing more than administrative issues. And schedules slip, of course. A scheduled meeting might have been delayed.