Hi,
Usually that problem is due to a bad connection of your iPad's LCD, what has to be done is:
- turn off your iPad;
- open your iPad (please watch the repair guide related to it);
- carefully disconnect (on both ends) the flex cable shared by the LCD and the Logic Board;
- carefully reconnect it, make sure it is well connected;
- try turning on your iPad to check that it is working properly.
If not than you should need a new LCD.
Hope it helps :)