Does the iPad give a countdown until the passcode entry will be unlocked or is it completely disabled?
If entirely disabled the iPad must be restored using iTunes. Sadly, if you have not been backing up in some way (such as to iCloud), this means all content will be lost. Though, purchased content can be re-downloaded after the fact.
If you have trouble with the following, do not click "Accept" yet - just reply back for further troubleshooting.
The following procedure is a special firmware recovery mode (DFU). It will re-install the iOS operating system on the device and clear forgotten/disabled passcodes.
Make sure you have downloaded and installed the latest version of iTunes before attempting this:
http://www.apple.com/itunes/download/
* Open iTunes
* Connect the iOS device to the computer
* Turn off the iOS device (hold down the sleep/wake button on the top) until you see the red slider and slide the red slider across to the right
OR until the device simply shuts off, if locked up.
*
Hold down the sleep/wake button AND the home button (on the front) for 10 seconds
* Release the sleep/wake button but
CONTINUE to hold the home button, until...
* iTunes should pop up and tell you it’s found a device in recovery mode, click ok and continue along for the restore
If it doesn’t work the 1st time, start from the beginning and try again. If iTunes *still* doesn't recognize the device, plug it into a DIFFERENT USB port and try once more.
Note: When the device first enters DFU recovery mode, the screen will be black.
At the end or the restore, you may be asked whether you wish to restore from iCloud. If you had iCloud enabled, you should do this.
Once the above is completed successfully, let me know and we can restore purchased content to the device.