Feeling reserved

I feel like I don't have anyone who cares for me, talks to me, and loves me. This feeling affects my mental health. I want to change my character. Five years ago, I lived like this but at that time, I also had no one to talk to or share with, yet I still felt happy and lived without any depression. But now I can't. I don't know what to do. When I see everyone, I compare myself to them. They have friends, but why don't I have anyone? I don't know why these thoughts come to me often.