how do I mend my relationship with my friends?

I’m in a group of college friends, we sometimes meet and hang out They’re nice people. It’s nice meeting them, we have fun but the problem is I’m not close to any of them. I don’t know the details of their lives as they know each others and its is all my fault. I’ve been distant, my problem is I wait for others to initiate if they don’t I don’t either. They sometimes joke about how they hold a feast whenever I come active

But I don’t want this anymore. So I tried initiating a conversation with one of my friends but it worked for one day. Then She commented on my insta post, I replied to her expecting an answer but none came , other than that I messaged her on WhatsApp asking what’s up , no reply…

there’s another friend I used to have from college but she’s not a part of this group. She hasn’t talked to me much since college ended except for one conversation which I initiated however she didn’t seem interested. Other than it has been almost a year of silence from her part. It’s weird because we were pretty close (or maybe just seemed) in college, she was one of the few people I felt interested in to consider my real friend. We had similar interests, she sent me memes on insta, she was often absent but when she’d be in college we’d be together mostly. She once even got angry on my behalf. I don’t know what went wrong.
I messaged her on WhatsApp a few months ago, no reply. Again messaged her this last week, no reply.

So I just assumed she might be busy or sick (she used to get sick very often).
but then yesterday I saw she was active on Instagram (i follow her) and I just felt betrayed.
I don’t know I miss her so much, sometimes I wanna cry.

I don’t know what I did wrong, we were so chill we never had a fight or an argument.