It sounds like he has a lot of social anxiety
, OCD, and low self esteem, try your best to get him to a therapist, and lots of compliments. I bet he doesn't take them well. Also, every day, make him go out more, and be more active, even if only 15 -20 minutes to start, then increase the time and level of social interaction as he feels comfortable. I overcame the "hermit way of life" by the above stated, but he will have to want to make the changes.