How is the strange, withdrawn and quiet personality caused? How to change it?

Actually, I haven't found a solution yet, but I will go abroad next year, so I will force myself to change.

First of all, you may not like the present situation in your life, but your subconscious may still be intoxicated by the breeze. If you can't make up your mind, it's hard to change, because no one will change their personality independently.

Secondly, if you are very popular, try to be like them and don't feel special. If you are unpopular, first find out who likes you better, then you can find a way to like her, and then you can be with her every day and tell the truth.

But in the end, you have to pursue a career that you are not interested in, right? Go home and think about what childhood wishes have not been realized, and work hard towards that.

Maybe a good impression of the opposite sex will stimulate people's self-motivation. Make a good female (male) friend, not something similar. It must be something you like very much.

That's all I can say. I don't know if it will help you. I hope I can help you.