At least ten percent of all cats develop a problem using their litter box. Some stop using it all together. Some use is sporadically. There are a variety of reasons your cat may be doing this, including a medical condition; conflict with another cat in the home; or a dislike of the box, the litter, or the location – there’s a reason cats have a reputation of being finicky. The best course of action is to prevent this problem, or deal with it immediately, by making the litter box as cat-friendly as possible.
One common problem is simply with the litter box itself. Make sure you keep it thoroughly cleaned, removing all clumps as soon as you can. Also, make sure you have enough litter boxes for your cat(s). You should have a box for each cat, plus one extra. Make sure her box is big enough, and easily accessible at all times.
Although we as owners sometimes prefer a hooded litter box, frequently this makes kitty uncomfortable. If your box is hooded and your cat is not using it, try removing the lid and see if this makes a difference. And finally, don’t make the litter too deep. Cats usually prefer one to two inches of litter.
There are a variety of other reasons a cat may be having litter box problems. For an excellent tutorial in correcting this behavior, go to ASPCA (American Society for the Prevention of Cruelty to Animals.)