Dear Harry_pem~
Thanks for coming here, I'd expect it is a very worrying ting for you to hear this from your freind, and puzzling too. Unfortunately there is no real road-map on how to fix things.
Actuality I don't think trying to fix the problem is your job. I have found that if somebody listens and cares that they have gone as far as thy can, and trying to go further, offer suggestions, to point out the good features in life is counter-productive.
Whet you can do that is the very best thing for your friend is to encourage him to go see his GP in an extended consultation and set out how he has been feeling and what has been going on in his life. After all there can be unpleasant things, but there should be good things too one can enjoy, it should not all be grey.
If he is under 25 and does not want to see a GP, at leat to tart wiht, I'd suggest takling ot or web chat wiht the Kids Help Line (1800 55 1800), or
https://kidshelpline.com.au/
It's hard to say more, life - as in maybe the break up of a relationship/job, illness or lots of other things could be causing his flatness and it takes a professional to sort it out and give a proper diagnosis.
In the meantime try for activities you have enjoyed together in the past and if appropriate say how glad you are he trusted you with is feelings.
Please do come back and say more
Croix
