If you restore with a 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.
You may have to 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. You must follow step 1 to step 4 VERY CLOSELY.