Blurry images

please help!!! i have had my casio exilim EX-Z75 camera for about a week now and at first it was taking great pictures. now suddenly out of nowhere all the images are turning out blurry. i have tried the auto focus setting and no luck. if anyone could help me, it would be greatly appreciated :) thanks
I bought two for Chrtistmas presents for my teenage daughters. They both have the same problem (blury pictures) and now one does not work at all. I thought maybe they were not careful with the cameras but now I am wondering if it is a problem with the camera.