What are my rights if I miss a flight due to a schedule change

I was booked on a flight from Dublin to London and the airline emailed me to say that the flight was cancelled and I have been booked on a flight the day before. If I had not seen this email (I didn’t see it for several weeks) and had turned up at the airport on the original date, what would be my rights? The original flight was cancelled and no flights from the carrier were going that day.