To set iPod's screen contrast, select Settings in the main menu. Then select Screen Contrast and use the scroll wheel to adjust the contrast.
To reset the screen contrast to normal, press and hold the Menu button for about 4 seconds.
Note: The contrast setting for the iPod models that have a color display is not adjustable. This includes iPod nano, Fifth Generation iPod, iPod with color display, and earlier iPod photo models. If you're not sure what iPod model you have, click here.