As an American, I can say that I understand the feeling you are describing. The first thing I will say is that you aren’t introverted - you are probably a normal person who has a normal amount of desire to interact with other people. What you are describing is social anxiety. I highly recommend going to therapy to tackle this problem directly.

I will repeat: Find. A. Therapist.

Trying to tackle this issue on your own, with help from random strangers on the internet, is playing life on nightmare mode. If you ever progress at all, your progress will be agonizingly slow because you will procrastinate and work inefficiently because there is no one guiding you through the process or holding you accountable for doing the things you know you should do.

Going along with that, is there anyone in your life you feel comfortable talking to about your problems, like a friend or family member? If so, tell them how you are feeling, tell them how you hope to solve the problem, and ask them to hold you accountable. The more people you have supporting you, the easier it will be to take the necessary steps to overcome your anxieties.

Next, accept this: you are going to embarass yourself. A lot. In fact, in large part, embarrassing yourself is the whole point of doing things which challenge your social anxiety. Socially confident people do embarrassing things all the time - they accidentally rub someone the wrong way, or tell a joke that flops, or accidentally say something inappropriate, or get shot down when they ask someone out on a date. The difference is, they feel momentarily embarrassed, and then they let the feeling roll off of them and move on with their lives. They don’t see their embarrassment as representative of themselves as people, or think that their social faux pas will define them for the rest of their lives. The way you get there is by making mistakes, embarrassing yourself, and then noticing that you still have friends and people still want to talk to you. Your social anxiety is driven, in large part, by the fact that you never make mistakes, because you never actually say anything that might make you feel embarrassed. You are still hung up on the fact that that one time when you were 11, the other kids laughed at you when you didn’t know the capital of Argentina or whatever. All the socially confident people also had that experience, and then had a bunch more experiences like it, and now realize that momentary embarassment is no big deal. You’ve been avoiding being embarrassed, so now it is your job to make up that lost ground.

This leads us to an interesting question - what is the point of socializing at all? Because the goal you’ve been striving for all your life - to not be embarrassed; to never have anyone dislike you - is the exact opposite of how you overcome your social anxiety. So what should your new goal be? Well, it should be to express yourself honestly and authentically, and to have fun.

Two important points here.

First, being honest and authentic isn’t something you just do. It is something you gradually get better at over time. Your social anxiety is your habit of compulsively hiding your authentic self from others so that you can never be rejected - it takes time to break down that wall, and learn to express yourself in a way that truly and succinctly expresses who you are at that particular moment, so don’t beat yourself up if you feel like you “aren’t doing it right”. If you “can’t think of anything to say”, it is probably because your anxiety is telling you that your real, lived experience of the world is uninteresting to other people - that anytime you speak, you need to be blowing their minds with something beautiful or inspirational or hilarious. But this is not true at all. You can just say things that you notice. For example, you can tell the cashier at the grocery store “I love these things. I buy them all the time” when she finds up your favorite cookies. Or if you pass someone walking in the park, you can say “Hey, beautiful day, isn’t it?” Or “A bit dreary today…” An even better hack, though, is talking about how you feel, especially when you feel nervous. Are you meeting a new group of people for the first time? You can just say “I’m feeling nervous meeting all of you for the first time because I want to make a good impression.” This will simultaneously do a lot of good things - first it will make you feel better because you are no longer nervous about trying to hide your nervousness. Sharing how you feel will make the others you are speaking to relate to you better, because everyone knows what it is like to be nervous when meeting a new group of people. And it will likely mean that these people will go out of their way to make you feel more included in the group since now they know that this will help you. A good phrase to remember is “autistically honest” - that is your goal. STOP trying to be smooth - just blurt out whatever is in your head at that moment without regard for context or social acceptability, and see what happens. You can always explain yourself later if people are confused.

Second, if you are authentic and honest some people won’t like you. People might not like you for literally any reason at all, from your hobbies to your job to your political views to your view of the world to what you named your dog as a kid. They might not like you because you have social anxiety, because you are trying to work on your social anxiety, or because you are less socially anxious than they are. To overcome your social anxiety, you must accept this - if someone doesn’t like you for who you are, then that just means the two of you are a bad match for each other at this time. Who knows, maybe in a week or a month or a year, one or both of you will change and you’ll be best friends. But even if that doesn’t happen, there are 7 or 8 billion other people in the world, and you can go see if they like you for who you really are. This, of course, doesn’t mean you shouldnt be trying to improve yourself - if very few people want to spend time with you because you never shower and smell bad, you shouldn’t continue not showering because “this is who I really am and other people just need to accept that”. But if you love playing Sim City: Skylines, then you shouldn’t feel the need to hide this part of yourself, and if others don’t like it then that’s fine - you don’t need them in your life.

It is also important to recognize that as you practice being authentically honest with people more and more, you will be more at ease doing so. You will naturally pick up on social cues easier and adapt them into your behavior without thinking or noticing. You will naturally gain new interests and opinions which align with the people you most connect with. You will find that you will say fewer embarrassing things, people will accept your flubs more supportively, and more people will like you. You do get better at socializing. But it isn’t something you consciously practice, other than by reminding yourself to authentically and honestly express yourself. If you try to consciously practice being liked, you are only indulging your social anxiety, and are not making real progress. So if you find that you are embarrassing yourself and getting rejected a lot, take a deep breath and remind yourself that you are on the right track - feeling this pain is part of the process of becoming a socially confident person.

So: go to therapy; get support from friends and family as much as you can; accept that you are going to embarrass yourself; accept that some people won’t like you.