I have lost interest in everything but I want to do something in life?

I am already into mid age of my life but suddenly I feel I am worth nothing for. I have lost interest and I don't know what to do. I have already my wife and son who are completely depend on me. I just dont know how to get focus in life. I feel helpless and feel to go away somewhere to reinvent myself. But I think that is not feasible. I am not gonna kill myself for sure.