First I agree, get kitty checked to make sure there is not any urinary tract infection. Then you can buy something called Nature's Miracle to spray on where your cat has peed. That will take the smell away and help to make it where it will not draw the cat back to the same spot. Its sold in most pet stores. If its fresh sometimes vinegar and water will work. If there is one area on the floor that kitty keeps going to you can put aluminum foil over it as cats hate to walk on that and it will detract kitty from that area. So once the smell is gone and you have broken the habit of kitty walking there you should be fine.