Help, I lost my cat!
We know how scary and upsetting it is to lose your cat. Take a deep breath and read this. You can get your cat back safe and sound.
If your cat got out of your house, make sure you check the hiding spots closest to your house. If your cat is not used to being outside, is shy or is in a new area, she is probably hiding somewhere very close to your house. Check storm drains, bushes, under cars (in undercarriages), up trees, under your porch, et cetera. Check all the houses, shrubbery, cars and drains within dashing distance of where you think the cat exited.
If your cat is used to going outside, or you think your cat is around and just doesn’t want to come back in, set up a humane trap with some tuna (instructions on setting a humane trap can be found here) and other smelly cat food. Put the trap in a safe spot on your property where you can supervise it. Do not leave it unattended for long periods or overnight. A big feast of smelly cat food may also lure your cat back to your porch.
Put your cat’s litter box outside where you can monitor it. If your cat is lost, he might be able to smell his way to the familiar!
Walk around with a plate of smelly tuna and call for your cat. Listen carefully. If you do not hear/find your cat, that doesn’t mean she’s not there — she may just be afraid.
This is very important — report your cat as lost to all the local animal control agencies, rescues and shelters. Put up flyers all around your neighborhood and call/put up flyers at local vets.
If your cat is microchipped, call the company she is registered with and report her as missing. They often offer tools to help recover your cat. If your cat is NOT microchipped, please have it done once you get her back! A microchip could save your pet’s life if he ever ended up at a shelter and ensure his safe return to you should someone find him and take him to a vet or shelter.
Talk to your neighbors and ask them if they’ve seen anything. Ask anyone who sees the cat to please call you right away. Make sure to check under cars. Ask people to beep their horns before they start their cars.
Post your cat as lost on Petfinder.com (under classifieds) and on your local craigslist (under lost and found).
If you live in an area with a lot of cats, make sure you look for where other cats are! Your kitty may have integrated into an existing colony of stray/feral cats. Check near dumpsters, in alleys, and around vacant buildings.
(Info copied from http://www.thecatrescue.org/lostcat.htm)