Ok, that sounds like maybe a hardware failure, if the volume buttons do not work; but before go to Apple try a restart and/or reset and see if that helps.
Restart: Hold down the power button until the power off slider appears. Slide it off. When the iPad finishes shutting down, hold down the power button again until the Apple logo appears.
and then a reset if that does not work.
Reset: Hold down the power and home buttons until the Apple logo appears. The iPad will reboot. This usually takes a bit longer than a restart.
Also, you can control the volume from the multitask bar. Double tap the Home button (on the face of the iPad) to get the multitask bar, then slide the icons to the right. You'll see several controls, including a volume slider. Normally this is for the Music app, but it also controls overall volume for the iPad.