Have you called & asked him or a mutual friend ,the not knowing is the worse part.
If u cannot reach him email him....tell him how u feel ,everything you are going thru and if he is a real friend he will respond.There are some ppl that when something happens they close themselves off to the world and just drown in sorrow,sadness or whatever....so since it has been a few days contact him tell him u r worried about him & if he needs someone there for him you are.
If he doesn't respond or take even a few minutes for you then he does not deserve you