It's quite possible to restore this image to almost pristine condition, however, not with the quality of the posted image. In order to restore the image, a color scan (which it is), at no less than 300dpi is required- with no image compression (totally destroys pixels).
Also, an image with this sort of damage can benefit from an additional scan. If I were restoring this image, I would scan the image and save the file, then rotate the image in the scanner, 180 degrees (looking at the image upside down), and scan again. Save that file. Both images would be placed together in a single file, lined up, and blended together (as light from the scanner passes over, and highlights the damaged areas, changing the direction of the light on the image changes how the damage is captured). Often, that process can minimize, and sometimes eliminate the cracks, which obliterate some portions of the face. This extra little bit of prep work can greatly reduce the amount of work needed, thus keeping the photographic qualities of the image. Perhaps you could try my suggestions, or instead, post the two scans.
