Depression

[Eric4Nitrous]

What exactly causes it? I've been deeply depressed for the past couple days and i don't know why. I've given up hope on everything in life..cars, women, my house work etc. I come home to an empty house every night and have nobody to talk to. I just feel like giving up on life in general and just taking a gun and sticking it to my head and pulling the trigger. I wake up every morning with nothing to look forward too..just sleeping my whole day away. Called into work for three straight days and my job is prolly on the line..but i just don't care. I haven't eaten anyting in the past two days. I went to the doctor and he told me what i already knew..that i'm depressed. So what's causing this??