first of all try to understand him, may be he is in trouble or something else, thats why he did'nt talk or messange you, if you are a good friend, you should call him or send a message to confirm that he is ok and everything ok with him, even if he is not responding you try to talk to him even not then just keep quit and pray for him that he should be ok,

just show your serious and true friendship.

regards

aamir