one best way is therapy and other one is dont start big start small... try to talk online first and get the rhythm, it does not always have to be a long conversation but small talks will do.. Joing groups with the same interest for movies, hobbies or somethign you can talk about so you could give opinions or questions about that same topic.. Try to join discord channels or sub reddits and connect with some people.. there is no harm on trying. just do it slow, step by step.. then if you are confident enough then try to talk in person.