How should you act with a guy who's really shy?

That is a little unusual for a guy to be that shy at 25? I would suggest making the first move...going to his house, or get together with a group. When you can actually be around him then try making the focus on him a little and just keep it light. He will come around as you start to make him feel comfortable but it will be your call. I would ask why he hasn't replied that is usually the easiest for them to be themselves? er him up and take him some cookies that always makes a man smile.