A Byte-Sized Friend (Hackers #1)

Chris Alten was a 13-year-old star athlete until an accident kills his father and leaves him confined to a wheelchair. His world has suddenly shrunk in size and he cannot adjust to the changes. He takes his frustration out on his mother and his friends. Then he meets a new, mysterious friend. This friend has no name and seems to know everything about Chris. Chris's friend expands his world through the use of virtual reality and teaches Chris to reach out and make new friends.
One of the new friends he makes is Ashlyn Jacobsen, a cheerleader who is anxious to prove she has more than just a surface beauty. Chris is surprised when he and Ashlyn discover that his mysterious friend is a computer program created by his father. The program was a pioneering experiment in artificial intelligence that has grown beyond its programming since the death of Chris's father. The program, which Chris names Harvey, now needs Chris's and Ashlyn's help to survive or it may be crippled in much the same way that Chris has been.
Having learned the value of friendship, Chris and Ashlyn must now come to Harvey's aid.