Depression. Thinking thinking that to!

Hello sir/madam, I am in full depression one month onwards. I working at bank as cashier. I unable also to express what was going in my mind.full thinking thinking that to regarding who r us? What is this life? Who am I? Headche also.my thinking fluctuates. Sometimes i suddenly come to my normal mind but one minute like that only. I can feel that difference. By reading some inspiring positive articles I can energies my self sometimes. But it's stay only limited time. again same thoughts I not at all belongs to this environment. Even though I recover my self from depression sometimes at past. It's hard to me now to recover.please help me how to recover myself from this mind and get in to normal permanently.For me no other problems also. I have kid also 3 years. Unable to take care of him. I unable to share this any body.plz plz plz help me...