Do check the other answers as Jared suggests. If you are in a play when you are overcome with stage fright talk to your director who might have experienced something similar and who is there to help you. Other members of the cast are also a good source of support. Discuss the problem with them. Again, we have all experienced stage fright at one time or another and while it can be paralyzing it is rarely fatal. Eventually you will have to deal with this problem yourself. Be prepared for your role. Stay focused on the job at hand. Stay positive about your ability to handle the situation. Remember to breathe! Everyone is on your side, rooting for your success. And then.....dive in, no matter how you feel. With experience, which is sometimes hard won, you will learn how to deal with these feelings of panic. If you are a solo performer ask your friends to help you to understand your situation.