To fix this, start off by adjusting the levels. From the "Images" menu, choose "Levels." It turns out that there's just too much blue, the other channels are fine, so start off by reducing the blue channel's contribution. Then, with the white dropper, pick out something that should be white (but it'll actually be a bluish tinge). Once you click on it, the image should look much better. Fiddle with the slider at the bottom of the dialog box until it looks pretty good.
A similar effect can be achieved with the channel mixer.
This has been your non-obvious Photoshop tip for the day.