My 14 year old daughter was always a shy child but now she has turned into a complete introvert. She doesn’t talk much and has very few friends.

Remember that a large number of friends is not necessary. One only needs one or two good friends for companionship. Quality is better than quantity in most aspects of life. Let her interact with people she is comfortable with and allow her the space she needs whenever she wants to. Also, encourage her to try new things, and watch her gain confidence. Confidence will make her feel powerful and good.