iBook stuck on pause

Try resetting your iPad. Hold down the sleep and home keys for about 20 seconds. When you see the silver apple, let go and let it reboot and see if that clears things up.

Another thing you can try is to force close the iBooks app. Double tap the home button. If you have iOS6 you'll see the app icons line up on the bottom of the screen. Scroll sideways to get to the iBooks one. Then hold your finger down on the icon until it starts to shake. Tap on the red circle to close the app. Single tap the home button to exit the mode.

In iOS7 double tap the home button, you'll see the app icons and a preview on the screen. Scroll sideways if needed to bring the iBooks app on the screen, then flick that preview window up and off the screen to exit the mode. You can single tap the home button or tap on the preview of the home screen to exit the mode.

your iBooks should need to reopen which should unfreeze it.

I'm sorry, if the reset or force close doesn't unpause it the only other thing I can think of would be to remove and then reinstall iBooks, which does mean you'd need to also redownload all your content as well.