Here are some tips for locating a lost turtle:
http://www.redearslider.com/lost_turtle.html
We've found in the past that turtles lost in the house turn up in the most unlikely places. They can squeeze into tight places - behind cabinets, under furniture - and go under clothing and in the back of closets. Look EVERYWHERE, even when you think she couldn't possibly fit. Be sure the dogs and cats are confined where they can't get her. Don't give up.
She'll be ok for a while without food or water. You can try putting a shallow dish of water in a location where you think she might be as the smell may attract her.
Good luck! Keep us posted!