Jumping the Scratch, by Sarah Weeks

After Jamie's aunt suffers an industrial accident that damages her short-term memory (essentially, preventing her from remembering anything that has happened since the accident), Jamie and his mother move in to take care of her.  This happens at around the same time that Jamie's cat dies and his father leaves them, so Jamie has gone through a lot and he is is very lonely.

Despite that, Jamie resists the attempts of a girl in his neighborhood to befriend him.  She's a bit strange and insists that she can hypnotize him.  While an odd statement, Jamie is curious:  could hypnosis help his aunt regain her memory? Secretly, he is actually hoping that her tricks might help him forget an even worse thing which has happened to him.

The story (and how it ends) is never really in doubt and most readers will have figured it out long before it ends.  However, that doesn't detract from a story that is fun and sweet.  The characters are memorable and Weeks keeps the story short and spare.  The gentleness makes the story suitable for younger readers, but it is far from childish and older readers will enjoy it as well.