It has been reported from the Holy Prophet (peace and blessing be upon his family): Whoever recites on the nineteenth night of the month of Sha'ban, a 2 Raka' prayer, reciting in each unit Surah Fatiha once, and Aya 26 and 27 of Surah Ale-Imraan five times.
Allah would forgive all his sins of the past and future, and accept all the prayers that he says in the future. If his parents are to thrown into Hell, Allah would take them out.