Ermm. open photoshop, press W, select the hair, press ctrl+u, play with hue, saturation. save.
if w doesnt capture hair correctly, select magnetic lasso (toolbar shortcuts to the left, 1st column, 2nd tool, right click, select) and do the rest. =)
Actually, here is a quick help for you
its a quick retouch. In order to create a great looking hair, it needs some serious time due to the blue filter on the image and due to hair being hard to create.