i lost my first ferret i ever had she was missing for 3 days we found her in the house across the roads garage ,she had gone in through the cat flap and was curled up asleep in the cats bed with very sore feet,my neighbour only noticed her because the cats wouldnt go in to eat there tea ,my ferret was eating it.
all i can say keep looking and ask the local children for help offer them a fiver for the one who finds him thats usually gets them looking good luck and hope you get him back