return labels

hi everyone a customer want to return a order and he bought the product on 20th may and want to return at 13th june and he wrote me this (I'd like to return my 113--4035459, as it isn't compatible with my intended use. I attempted to obtain a return label through the amazon return center, but the process did not go through. Could you kindly provide a UPS drop off label for the return? Thank you for your assistance). so what should i reply him and how can i generate return label for him kindly guide