Be sure to go to your LOCAL SHELTERS with a photo and report the pet found. They have a board for both lost and found pets. Remember, NOT EVERYONE is on Social Media. There's some excellent advice on Missing Animal Response Network on Facebook as well as their website. Additional advice can be found on the website under the drop down menu labeled lost pet help.
If able, try posting on your local nextdoor app, findingrover and watching craigslist. Also, take flyers to vets and shelters. Try taking to a vet to check for a microchip too. Be sure to ask for proof of ownership by either vet records or a picture from the phone.
Shared, please contact the animal shelter, his owners may not use social media. Thank you for keeping him safe! Make sure if someone tries to claim him they have proof of ownership.