I know how you feel as I have been in situations in my life where I feel that I want to be someone different or want to change in such a way that it might make me look and feel like I'm a different person than I was in times past. If this is the case then let me assure you that you can change the outside all you want and it won't make much different to how or who you ate on the inside. But there is great news! The path for what you seek is the same. If you truly wish to gain enough power to alter your physical features, you first have to start from within. In magic, the power to change or alter things comes from the power within yourself. This includes working on your willpower, focus, visualization, self confidence and learning who you are, how you truly behave, how you learn, accept your weaknesses and strengthen them, acknolodge your strengths and use them to your advantage as well as many other things. The advise and knowledge the others above have shared are true and very wise words indeed. Focus on what you like about yourself and the good things you remember from your past. Write down what you want to feel or look like on a piece of paper in as much detail as possible. Start reading and learning about good meditation techniques, energy manipulation, spells, wizards (or whatever magical type you feel drawn to), occult sciences and anything that any of those topics tell you to read on in order to get a firm grasp on the topic. Come back to your list you made each week and mark off the things you have suceeded in accomplishing and write other things down that you might have found that you need to learn about or work on. If you find that your thoughts are getting worse or you feel more depressed then you need to talk to your parents or a councilor right away. If, in a month, you still want to change then come back and I will give you a spell to cast. The trick is, is that you have to have confidence in yourself, be ablke to focus and visualize intensly and have a good basic knowledge of how magic works to be able to cast the spell and have it work. You can find many threads and info on this site to point you in the right direction. Read the articles and search the forums to get the ball rolling.
-Tonkor The Wizard