You may loose all your data but this should get you in:
1. With the device off, press and hold Volume Up and Power. 2. Release the Power button when you see the Samsung logo ( about 3 seconds), but continue to hold Volume Up until the recovery screen appears. 3. Use the Volume buttons to navigate the menu and select wipe data / factory reset. Press Power to continue. The Galaxy Tab should then go through the hard reset process ( formatting user data). 4. When formatting completed, navigate to select Reboot system and press Power. The Samsung Galaxy Tab is new again.