Is the soil currently moist at all? If so, please don't water it. We have no idea where you are, so I don't know what kind of temps it has experienced so far. Bougainvilleas can take light frosts and even defoliated plants can fully recuperate. Bougainvilleas thrive best under dry conditions..., especially one that has been stressed. Don't feed it either. These plants do better with though love. Leave it be until it shows signs of new growth.
