The best way of dealing with depression is by being close to your friends and family members. You need to share with them what is happening to you so that they may help you where possible. You can also seek professional help from support groups or keep up with social activities even if you do not feel like it. Check out http://www.helpguide.org/mental/depression_signs_types_diagnosis_treatment.htm for more information on depression recovery processes.
find something you like. ex: i like the color blue and 70 degree weather. dream about things you admire. ex: i want to be superman and i also want to be like elon musk and be worth 2.4 billion dollars by the age of 36. neither of those are looking too good for me right now but you know what? that's okay. we are all important in this world, including you. sometimes its just hard to see that. I hope this helped. if it didn't i am really sorry
Watch what you eat, sugar is a drug that gives you highs and lows, try to avoid it. Get some exercise. Its good for your physical and mental health. Get some sunlight - its natures anti-depressant. Talk to friends, family, councellor, therapist, whoever.... sometimes just talking makes you feel better. Check out http://www.amazon.ca/Feeling-Good-Handbook-David-Burns/dp/0452281326 I've heard its really helpful.
The last resort if all else fails is medication. Talk to a doctor about that.
Go for a run. :) Hang out with friends. Join clubs or any hobbies you like. Keep your self busy, don't be alone, not in your room or anywhere lonely. Do things that just keep your mind off of things. :)