What you’re saying sounds mostly psychologically-induced. Ask yourself whether deep inside you have a lack of self-conscience towards other people, people you don’t know or people you would like to get to know more (e.g. Pretty girls).
To alleviate your blockade you need to be more confident in social interactions - this can be trained.
For one you need to get used to talk more in general, and especially more spontaneously, I.e. Without preparing what you say.
Find people you’re confident with, and who accept you as you are. Then find subjects that are interesting, yet a bit off everyday topics. Then combine these two and have regular chats, which should become a fixed part of your daily routine. You might want to get informed on subjects that go more into depth (certain type of literature, political issues, scientific topics, etc.), which makes things more interesting and poses more of a challenge. In ‘talk more’ I mean you’d have to spend more time of your day for chats and talking, not that you should expose others to extended monologues of yours. Pay heed to the reaction of the people you talk to - even if they don’t say anything, their facial expression and their gesture give hints enough on how you should proceed - become more passive, ask questions or stay active and continue speaking. Find out how you want your self to be perceived. Which famous person, which movie/game character talks and acts the way you’d like to appear?