what do I do??

I'm not one of those teenagers with a ton of problems and a tough life. I have a nice looking life, a ton of friends, a good family, food, etc. But I'm not happy. I feel so greedy for it. I feel like an awful person and I should be so grateful. I am grateful thought, just not happy. I put on a big smile for everyone everyday so they can't see anything. It's like I'm hiding. Inside there is this manipulative force that gives me temptations. I can't describe it because it scares me and makes me feel crazy. I don't want to get help. In a way I kind of like it but I know that what I do is not healthy. Am I selfish? I already regret posting this. This is not real life what is happening. How can I make myself my regular self again?

No, you're not selfish. Too often it is assumed that depression is always situational. While that may be the case for some, it is far from always the case. Depression can't quite be explained. As it seems that everyone experiences it differently and for different reasons.

As for how to make yourself your regular self again, you've already achieved the first step. Realizing that something is wrong. Now, the best thing I can recommend you do is reach out to someone. Have you tried to speak to a parent provided they'll listen? Have you tried speaking to your school counselor? It might sound scary but it does help to talk. It not only helps to find help (such as therapy if it's a possibility) but it helps because sometimes talking is what we need to do most.

Hello & Welcome, Raychill.
What Bronzeowl said: realize something is wrong and then find out what is wrong. As it is possible more than one thing may be going on with you, I suggest getting a regular medical check-up, too.