Locked Out, Forgot Lock or Restrictions Passcode, or Need to Restore Your Device
8. 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
Yes, all data will be lost, but the apps are purchased using an Apple ID, so if he signs in with the same ID after restoring, he can redownload apps. See http://support.apple.com/kb/HT1212 for forgotten passcode information.