(CNN)– Getting a song to hit in the summer can change a career — just ask Katy Perry or Robin Thicke. Before the reign of "I Kissed a Girl" in the summer of 2008, Perry had been tirelessly striving. When the world hands you lemons, what do you do. it’s true that music is the ultimate salve. Here are all the tunes that kept us sane and as positive as…