What to do when you’re all alone?

I hate this feeling I used to like being alone and preferred that but now I don’t want to anymore. I always feel so lonely now and I don’t have anyone to talk to and I have random moments where I want to cry. It’s so hard to make friends. I go out by myself few times and I notice people being with their friends and nobody else is really alone except me and it’s almost caused me to cry in public knowing how really alone I am. What do I do?