I suspect a good part of your problem is that there isn't much detail there to begin with. It looks like the child's face was somewhat overexposed in the original.
You might try selecting just the child's face area and playing with curves to see if you can find a magic combination that will help. If nothing much helps when doing that, it may be because there just isn't any infomation there to manipulate.
Most of the books I've seen on PhotoShop have sections on restoring old photos. Maybe a little time at the nearest library or bookstore browsing through the PS books would give you some things to try.
Elvis has left the building...