My students are shocked when I tell them that when I was in college, I was a loner, but then I went into teaching and became more sociable. :) I think you probably need to put yourself in various positions in which you MUST talk in front of people. And Hery's on the right track: practice in front of your friends first.

I had that problem few years ago. But I am better right now. I tried to present my project in front of the class when I was freshman in university. Approximately, the number of student in my class was 35 students, and that was about Algorithm of programming. I had prepared the whole things well. But the problem was I got stage fright when I wanted to present my project to the audiences. And the result was failed, because I was speechless at that time. So, for the next presentation, I tried to be calm, confident and bold ,took a deep breath. And before the presentation day, I tried to explain the materials which I would present to my friends by fantasizing that my friends were the audiences.

Before a speech or performance spend some time alone and do a mini meditation. Sit down and close your eyes. Take slow deep breaths and visualize yourself doing your speech perfectly. Everyone gets nervous so it's not only you. Don't tell yourself that you will forget your lines or gestures as that is not positive reinforcement. See best results and you will get best results.