Please help my cat refuses to use the litter box.

You say he will go on paper sometimes; try shredding up some newspaper and placing that in his litterbox, and then VERY slowly start to add litter (and I mean VERY slowly, as cats are very finicky!) until he is used to using litter.

Has he been brought to the vet to clear any chance of having a UTI or other health problems? Cats urinating outside of their box is a common sign of a health problem, or that something just isn't right.

We will probably need more information. How old is he? Where is he going if he is not going in the box? He may not like the location of the box in your home. Did you try re-locating it? Try a few different litters. Also, there is a product called "Yesterday's News" that is not the same texture as litter. You can purchase it at pet stores and possibly at the vet's office.

try shredding some paper and putting it in the litter box. Is your litter box enclosed or open some cats dont like the enclosed ones.