we cannot trace/track phone numbers. we are a web forum.
if you think that your friend is a "missing person" and this is an emergency then your best bet would be the police.
if you were supposed to meet your friend and just lost sight of eachother (or some other non-emergency situation similar to this) then just call him and ask him where he is.
there are ways to share gps data if you have certain apps, but unless he is set up for this then you wont be able to trace him. that and tracking without permission is illegal.