Depression

I don't know if you know this, but I have had depression.
You're thirteen, you might say. What reason would you have to be depressed?
No reason. My life is good. I don't have any problems. Nothing horrible ever happened to me. But like many teens out there, I got depression.
Everyone can be sad sometimes. Being sad is good when it's short. But when it stretches into something that lasts weeks, maybe months, that's when it gets out of hand. That's when it gets horrible. I could put in a whole lot of not-so-polite language as to how horrible it is.
If you haven't had it, depression is undescribable. It's the kind of thing that you can understand but not feel. For me, it was like there was a fist around my chest, squeezing harder and harder. Sometimes I would get queasiness or headaches. It wasn't like I didn't know something was wrong with me. I did, but I felt like no one knew and no one cared.
Which brings me to another point. If you are depressed, you will know what I mean when I say that you feel isolated in your suffering. You feel like you're the only one. And you're afraid to talk about it, because someone might dismiss it as something trivial or make fun of you. But you can't help but want to scream your suffering, let it out somehow. Maybe you think about suicide.
All I want to tell you is you're not alone. And as much of a failure you may think you are now, you're not. I guarantee it. Someone out there does care. Someone does love you. Someone out there will help you get out of it. You don't even have to tell them anything if you don't want to. Just know that you're not alone. And that it isn't permanent.
This is my best effort to help. If you are depressed, you may not believe that stuff up there. But I have been through it. I'm not going to say that if I can get through it, so can you, because that isn't always true. But you don't need to suffer. 
Come out of the dark. When you see light again, you'll find that you missed it.