I'm not religious but I need prayers

You did the right thing reporting him missing to the police.

When they get dimentia, it can be tough...

A few years back there was a tragedy around here with an elderly man with dimentia that walked out of the house one night and the family and police could not find him. They even put out a community bulletin email so if someone found him they could report it. They found him the next morning frozen to death from the overnight cold. He wandered out of the house and forgot how to get home.

Most of the time they find the people a few hours later. Hopefully they will find your grandfather soon. At least now that you reported it, there's a better chance that someone can find him and get him back to the family if his memory is failing him.