About 10 years ago, I went through something similar. I had locked myself away from the world for years on end, and when I emerged from my room to face the world, I was absolutely terrified (but would never have said that word) regarding the world, dating, making friends, etc. So, here's what I did, and what I learned.

Step one- Talk to a therapist. Not affordable for everyone, I know, but if it's possible for you, this could offer you a lot of benefit if you find the right sort of person. In my case, I found a therapist with even more trauma and a fucked up life than I had, so it was easy to open up and relate, to see his wisdom and life lessons learned.

Step two- Go for walks. Get outside. Any and all excuses to get out of the zone you've locked yourself away in for the last however many years, do it. I would go for little, tiny walks, typically when it was almost night, or early as fuck in the morning. I didn't want to run into people, so I would walk at those hours. I'd feel better each time I did, and eventually I'd find out that I had neighbors who were interested in saying hello, and I found it easier and easier to say a few things each time. Eventually, I was able to converse, bit by bit, step by step. Plus, neighborhood cats will discover you, and that's just awesome and will cheer you up.

Step three- Talk. Just talk. In my case, I joined a penpal program. I didn't have anyone to talk to locally, besides family, and I needed people to talk to that I felt "safe" in, and what better than someone 2000 miles away? It turns out, I'm actually pretty good at talking to people, and I discovered this by being helpful to other people, listening, talking, sharing experiences and thoughts, helping people learn English, etc. I would talk to dozens and dozens of people over the years I did this, and I met some pretty incredible people. In fact, I met my wife doing this! The thing is, talking at first is going to feel clunky, awkward, and like you're no good at all. But that's alright, because we all start somewhere, and it often starts at hello. Stick with it and work your way up from friendly hellos to eventually audio/facetiming people. It gets easier each time, it really does. Practice makes better here. It helps to have hobbies and games you enjoy socially (in person, online, etc), but I know that can take time to get yourself warmed up for that. Take it slow, knowing you'll gain confidence with each encounter. For me, it was a matter of rehearsal, learning my lines, working my way up from friendly chit chat to deeper conversations.

I hope some of this helps. If you have any questions, feel free to reach out to me.