All my ex friends have moved ON?

I'm sorry to here that. I lost all my friends too. I'm 22 years old and everyone I hung out with back in high school doesn't talk to me either. If I see anybody in public, they don't want to talk to me. Although, I did abandon a lot of my friends because they all became heavy drug users. That was 2 years ago, and I still can't make any new friends. I feel so alone sometimes. I've tried talking to random strangers when I'm at the mall or the coffee shop and nothing seems to work. I hate being so left out of everything. It seems like everyone has a life but you, huh? That's how I feel. I really wish I could help.