FORCE IPAD INTO RECOVERY MODE
1. Turn off iPad
2. Turn on computer and launch iTunes (make sure you have the latest version of iTune)
3. Plug USB cable into computer's USB port
4. Hold Home button down and plug the other end of cable into docking port.
DO NOT RELEASE BUTTON until you see picture of iTunes and plug
5. Release Home button.
6. iTunes has detected iPad in recovery mode. You must restore this iPad before it can be used with iTunes.
7. Select "Restore iPad"...
1. Data will be lost if you do not have backup
2. If you did not do step 4 properly, start all over again.
Locked Out, Forgot Lock or Restrictions Passcode, or Need to Restore Your Device: Several Alternative Solutions
Forgotten Restrictions Passcode Help
You will need to restore your device as New to remove a Restrictions passcode. Go through the normal process to restore your device, but when you see the options to restore as New or from a backup, be sure to choose New.
You can restore from a backup if you have one from BEFORE you set the restrictions passcode.
Also, see iTunes- Restoring iOS software.