Okay. Could be a water problem, have you been keeping it well watered? If not, do so from now on. Otherwise, if the leaves were newly opened, the sudden drop in temperature this month compared to the much higher ones last month might have caused them to die back. Check the stems for signs of scale or any other insect infestation, and if the plant is in a pot, turn it out of its pot and check the rootball - if the roots are non existent, you may have had vine weevil attack.