Gyroscope orientation is all relative, so whatever direction you are facing when you open the app will become 'forward' in the game. Exiting out of the app and reopening it should cause the gyro to recalibrate to whatever new direction you are facing. The app also recalibrates in between games. Face your desired direction as it fades out, and when it fades back in you will be looking forward again.
Please reboot your device completely by holding down the power button for a few seconds and then sliding the slider that appears. If that does not fix the problem, shoot us a message using the form below and we will help you out.