Send ambiguous messages to chasing girls. She never answers. What should I do? He is quiet and never talks about it.

This shows that she may not feel as strongly about you as you do about her. In this case, if you have been trying to approach her in various ways to express your mind, it is likely to be counterproductive, that is, she may resent you. Feelings need to be cultivated, and it is also a long-term running-in process. Moreover, for a quiet girl who has never been in love, you need to prove that you are good to her with practical actions, grasp the scale, and let her gradually feel your concern and care, so that you can further communicate with her.