Go out and bang his food dish or can and call his name over and over. He's probably under a car, in a garage, under a porch or up a tree - scared stilff and hungry and dearly missing his home! Do it every hour - especially when its quietest outside - call loud and then stop and wait and listen for the tiniest little "meow." I found one of my cats way up a tree - like 4 stories up!! His "meow" was so little I could barely hear him as he was so far up!! Go around the block and down the alley - across the streets too - good luck. Let us know what happened!!!!!!!!!! Post reward signs in the area too.
SIMON IS HOME! He spent the day at various locations around the neighborhood and finally made himself known in my neighbor's back yard, huddling under a bush and very exhausted and scared. He is now under house arrest. He has eaten and is very tired, but happy and healthy. I thank you for your advice and good wishes. A happy ending.