Press and hold the Sleep/Wake button and the Home button simultaneously for at least 10 seconds. The Sleep/Wake button is the hardware button located on the top edge of the iPad. The Home button is centered under the display.
Do not respond to the slider that appears at the top of the screen. Continue to hold the buttons until the Apple logo appears on the screen. Wait until the Apple logo disappears and test the device.
Reset the iPad settings if the device still doesn't respond following the reset. Tap the "Settings" icon on the home screen of the device, followed by "General." Tap "Reset" to go to the reset screen. Tap "Reset All Settings." Your data and files are not affected.