Post it in Nextdoor.com, that may help, also post flyers. If you can, wAlk around where he was Las seen and call him he may follow your scent and go back home. Also post flyers all around where he got lost and where he was saw last time and further. I recover a cat after two month due a flyers, I place them further any time and replace them. My cat had no collar mother microchip, but I never gave up. Don give up but act.