You NEED to find him soon. Can you make a search party? I know that sounds funny, but you need to look everywhere. In every bush, behind trashcans, everywhere because if he goes into hybernation he will die. Captive hedgehogs cannot survive hybernation. :*( I would also throw some old laundry or towels out as they love to hide in those. Just anything that you think will attract him. Also, make sure that leaving the food out isn't attracting larger animals such as racoons and possums.