hobby - honestly just try a bunch of different things for a while and you might be surprised what you like. Take up gardening, hobby games (build/paint miniatures and play 40k, battletech, etc.), hiking, really anything that requires some focus and a bit of work. In a lot of cases its more about having something to do other than work and being tired/lazy/depressed at home vegging out and/or getting into a worse headspace.
mate/social circle - honestly this can be hard (especially if you’re really introverted) but getting into a hobby can open new doors. Also think about getting a pet or two. Animal companionship can really be more than a substitute for other people and fill you with all sorts of joys.
life purpose - this is really hard but honestly you and in complete control over this if you push yourself hard enough. Literally just choose something. It can even be to just live as long as possible despite any shitty circumstances (doesn’t have to be some grand unachievable goal).
I really hope I'm not stepping out of line but your message seemed like a call for help. I've had my own long spells of depression and some of the above have helped me a lot. Please also consider getting in contact with professional help if it’s really getting bad. Forget about shame, nervousness, or whatever had headspace your currently in, your life is 100% worth more than any of that.
Thinking about exercise, thinking about cleaning my room, thinking about doing laundry. I can sit in misery thinking about what needs to be done, or I can just start working.