Work in retail.
Being desensitized is everything imo, the more you talk to people the easier it becomes and the easier it becomes for them to talk to you.
Also to find common ground with people (which really helps) you need to expand your own interests, you may impress people with whatever skills or knowledge you may have but they won't say it and they certainly won't keep you around for the sake of it. People want to surround themselves with others who share their world, their interests, their concerns, so if you take an interest in their lives and their interests they'll take an interest in you.
How's it going? How was your weekend? Are you feeling alright?
What are you studying? Where do you work? What games do you play?
People love talking about themselves and the more you know about them the more things you have to ask about and in short order they'll get embarrassed and ask about you and then if you tell them things that they can ask you about later that makes it easier for them to talk to you.
Getting out of that rut is hard, best of luck to you and stick around I'm sure you'll meet some new friends here too