Are they declawed? This can cause it as well, but to get them reprogrammed immediatly to a litter box you need to get a large dog cage and confine it there with its bed, food water and litter box. It may have picked up on a bad habit and needs to be broke of it, providing there is nothing medically wrong. Also help by keeping dirty laundy towels and any clothing lying around picked up. But the confinement will help retrain her, and then let her in a small are after 2 weeks with the littler box and then from there back to free roaming, again IF there is nothing wrong medically.....