The default PIN code is 0000. If you have changed it and forgotten the PIN for your GDR11 you can reset it.
If you cannot remember your newly set pass code then the default override pass code:
Press the blue, green, red and yellow buttons twice, quickly one after other. (Press the blue button twice, then the green twice, then the red twice and yellow twice)
You can only reset the parental control pin code by using the parental control menu.