If it's been disabled by the passcode having been entered too many times then see this article : http://support.apple.com/kb/HT1212
If you repeatedly enter the wrong passcode, your iPhone, iPad, or iPod touch will be disabled for longer intervals before you can try again. After too many unsuccessful attempts, you won't be able to try again until you connect it to the computer with which you last synced it.
Message was edited by: King_Penguin
Then from http://support.apple.com/kb/HT1212 :
If you restore on a different computer that was never synced with the device, you will be able to unlock the device for use and remove the passcode, but your data will not be present.
If you've backed it up to iCloud you could then restore that backup
You may need to put the iPad into recovery mode in order to be able to reset it via your computer's iTunes : http://support.apple.com/kb/ht1808