You ignored the warnings. Makes sense--you didn't want to read the spoiler-y way of avoiding the game-ending Skyward Sword glitch. "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," a Nintendo representative confirmed last week.
If you've experienced the Song of the Hero glitch, you're not exactly out of luck. Before deleting your save file and starting over, Nintendo is now offering two solutions to fix the problem.
The first solution involves mailing a physical SD card with your save data to Nintendo for repair. "For information on how to send your save data to Nintendo, please call 1-800-255-3700."
The second solution is easier, but will require a bit of patience. "We are also planning on releasing a program that will repair save data for those who have their Wii connected to the Internet," Nintendo's support site reports. "We are currently working on preparations for the release of this program."
Nintendo's language suggests the online repair program will be available soon. It may be worth skipping a trip to the post office while waiting for this workaround to go online.