I am very depressed and i have been for a very long time now but i actually have no reason to be sad, i don't understand why?

Long-term depression: Long-term depression needs care. I hope you're working with a primary care physician to care for your general health, and a psychiatrist and therapist to treat your depression. There may not appear to be a "reason" to be sad, but you still need help. Depression can be a very limiting condition, and can interfere with accomplishing your goals in life. Please get help as above. Be well.