Are You Experienced? by Jordan Sonnenblick

Rich is a fifteen-year-old guitar player frustrated with his father and his life. Rich breaks into a locked cabinet that holds his dad's prized possession: a guitar signed by Jimi Hendrix. Before he knows it, Rich is transported to the side of a road in Upstate New York with a beautiful girl beside him. Shocked, he comes to realize it's 1969, he's at Woodstock, and the girl's band of friends includes his fifteen-year-old dad and his uncle, who's still alive.  from the book cover.  Find in Young Adult Fiction Sonnenblick