Have you tried internet to meet up with old friends like facebook or apps that show you people in your area? There are others out there who have found themselves sort of stranded. For me my friends moved on, either hung out with workmates, started a family or we grew apart. But in last few years I met a couple of friends - one was through facebook even though it does my head in seeing how good other peoples social lives are compared to mine. The other was through a mental health group. You could try checking out the groups - sport, art, martial arts, pool/snooker etc. or volunteer work . Just keep searching. go on a dating site and say you are also interested in just being friends. Maybe you like your own company, that's what I found about myself I'm such an introspective artistic type. I think this made people question me at school . I hope u can find something worth trying.
Meantime u can read some self help books download them on your kindle. Ones like heal your loneliness, inner child, dare to connect, that sort. I got into music again and read graphic novels, love comics now.
Best of luck, there's someone out there for you