What happens to old friends?

I have a friend from New York that I used to be in touch with fairly frequently. We would IM weekly at least. For the last couple of months he has dropped out of my life. He is a good friend who has been like a life line to a saner me from before I moved to this culture shock of a place. I miss the conversations, the mundane chatter and the sharing of discoveries. I have no one else to share this with, except sometimes K, but that's not the same. My friend and I have mutual ground (from the School of Practical Philosophy), a similar ideology, philosophy or whatever. We spoke the same spiritual lingo. I miss that. A lot. I wish I knew what was happening in his life that he has shut himself off from something so simple as just talking (via the internet). I heard he was ill, and it grieves me that I don't know what is happening.

When people far away loose touch, how can you know if they are still there? There is a void living inside me. Like I have lost something precious and don't know where to search to find it.

I hope he is well.