Johnny Angel by Danielle Steel

Summary
Johnny Peterson could light up a room with a word or a smile. He had a future filled with promise--until he stepped into a car on prom night and, in an instant, it was all taken away. In the months that followed, Johnny's family and his high school sweetheart, Becky, struggle to put together the pieces of their shattered lives. No one is more devastated than Johnny's mother, Alice, but amid the heartache, something miraculous is about to happen. When a sudden illness sends Alice to hospital, a glorious vision comes to her--there, standing before her, is Johnny himself, gently urging his bewildered mother to be strong for her splintered family.

Through a season of hope and healing, Johnny will walk by his mother's side, leading his parents, his girlfriend, his sister and his brother out of their grief. But as Alice is about to discover, Johnny has returned not just to help those he loves, but to uncover a purpose even he cannot comprehend--one that will change them all forever.