i feel you on that but my reason is because i have PTSD. maybe you don't feel loved by your friends or family? what is it you think might be the problem? be free to tell me i can try my best to help you.
Has there been any changes in your sleeping schedule? or do you find that you feel this way more often when it's cloudy/raining? because both can cause a person to feel depressed. Other then that it could be a stress related issue, or if you're a teen (girls have a bigger change chemically then guys do so they have a higher chance of this happening) then it's possible you're going through a chemical imbalance. Like the profile pic btw.
Depression is situational or chemical as far as I know. Change your environment/relationships/circumstances to get rid of situational depression. If it's chemical, research herbs to see if you find anything that helps. My psychologist recommended St. John's Wort. If you are suffering from SADD, Seasonal Affective Depression Disorder, buy a full-spectrum light and follow the instructions to use it.