why do i feel this way?

i'm so depressed...why? things starts to fall apart..it just seems nothing goes to how i want it to be. i feel so alone. that each time i think why this is happening to me.. tears always fall from my eyes... i wish i can go back to the time where things were so good... i dont know what else to do..this emotions inside me.. that starts to frighten me.. Please .. help me ... im so lost...