Call for kitty late at night or very early in the morning when it's quiet. Often they are not far away but are afraid to come out. Sometimes they get accidentally shut in a garage or shed -check your house and ask neighbors to check theirs. Put something of yours outside, food and kitty's litter. That may tempt kitty. Put up posters and post on social media. Notify your local animal shelter. GO TO THE SHELTER IN PERSON to check for your cat. If all else fails get a humane trap and put sardines in it to catch kitty.