I suppose cry a lot.
Locked Out, Forgot Lock or Restrictions Passcode, or Need to Restore Your Device
7. RecBoot: Easy Way to Put iPhone into Recovery Mode - if all else fails.
Forgotten Restrictions Passcode Help
If this method does not work, then you will need to fully Restore your
device as New
Apparently my restrictions passcode became unusable after the 3GS on which it is set was updated to OS 6.1.3 with the restrictions on. I have a record of the passcode in three places for safekeeping, and suspect a bug in the update process. I'm hoping Apple might fix this with the next update to allow the existing restrictions passcode to again unlock the phone. In the meantime, I'll try some of the various tips others have posted on this and other pages.