Cats are sensitive to smells so use familiar scents to guide him home. Put out UNCLEANED favorite clothing/blanket that smells like owner and cat. Place favorite stinky food like tuna or KFC, preferably in a humane cat trap which can be rented from local shelter. Walk around neighborhood calling cat and shaking treat bag. Post on the free services Nextdoor.com and Pawboost.com. Go to each neighbor house with pics of the cat because sometimes they get shut in garages or sheds accidentally. Check out the shelters in person every other day and ask to see ferals because sometimes they get scared and act feral. Professional trappers also spread owner's urine in yard area. Hopefully you can be reunited soon!