Nintendo has announced that there is a monster bug in Skyward Sword that essentially breaks the game. The company has apologized for the oversight, and revealed how gamers can avoid it.
"We have been made aware of the issue that results in being unable to progress in the Song of the Hero quest," Nintendo said of the situation. "If the game has been saved after completing the sequence of events, it will no longer be possible to proceed through the game on that save file. The only options at that point are to either start the game over or to use an earlier save file to continue."
"This issue WILL NOT OCCUR if the Fire and Water Dragon songs have already been collected before collecting the Thunder Dragon's song."