While some factors are genetic, Rutkowski says that growing up in a musical environment strongly influences whether someone sings well and with confidence. It's very important that you work with a good coach. Often, with singing teachers, they teach technique. But singing is so psychological and emotional.
People have a lot of emotion when it comes to that. Look for a coach who understands what's going on with you psychologically so that he can bring you back. Singing practice and training involves generating a sense of vocal freedom; this is what you see when you see someone sing in a moving, beautiful but seemingly effortless way.