Is it normal friends don't talk to me after school?

I graduated highschool last year, however now my friends have completely stopped talking to me. I didn't have many friends, around four or six but we were really close; had all our classes together, hung out, went to eachothers places after school.

Now it's like they've abandoned me. I only ever talk to them on Facebook, but it's always me starting the conversation which made me feel like I'm annoying them, so I've stopped messaging them. It's been around two months now and none of my friends have even messaged me a hello, I feel so lonely and sad as they were the only friends I had growing up. Does this happen to everyone or is something wrong with me?