Why Isn't My Cat Using the Litterbox?
If your cat stops using the litterbox, there could be a number of reasons ranging from dislike of the litterbox or the litter to an underlying medical condition. There is always a reason for a cat to stop using the litterbox; punishment will not correct the behavior.
You should make an appointment with your veterinarian for a health evaluation of your cat. If your cat is repeatedly unable to pass any urine and is excessively licking his/her genitals, this could be signs of a medical emergency and your cat should be seen by a veterinarian immediately.
Ensuring your cat is spayed or neutered will also help reduce inappropriate urinating.
If a medical condition is ruled out by your veterinarian, it is best to discuss with them other behavioral possibilities and approaches to correct the behavior.