If clearing cookies and data does not work, try closing down safari from the Task bar.
Double click the home button to bring up the task bar, find the Safari icon and press and hold it unitl the icons start to wiggle. Then tap on the ➖ badge to close it . Click the home button again to to return to the home screen, and then try opening Safari again.
If it still won't work, try resetting the iPad. hold down on the Home and power buttons until the Apple Logo shows up. Ignore any sliders that appear. This is the equivalent of a reboot, not data will be lost.