There are several ways to check people: newspapers and television. Coverage is wide, but attention is not enough. Southern Metropolis Daily and Guangzhou News TV are famous for reporting Guangzhou people.
Check online, or call 1 14 to see if the former factory still exists. If so, check with the personnel department to see if anyone knows his contact information.
If you know where he lives, go to the local police station to explain the situation and ask for help.