Have you tried rebooting the tablet? If not that would be my first suggestion.
If that doesn't do it, and you can't access the calibration screens at all (to recalibrate the device), the only other option I can think of that you can do on your own is a "Hard Reset", but that I would really save for a last option thing. Why? Well, because it will wipe all your personal data.
If the device is still under warranty, contact the manufacturer and they can repair or replace it. If it isn't, and you don't want to wipe it with the "Hard Reset" (which is not guaranteed to fix the problem btw), then I would contact a local tech or tech shop to see about having them look at it. It may well need the display replaced.
NOTE: Doing this will clear 'all' the data on your tablet, so it is suggested you not choose this option unless you have to, or aren't worried about losing anything on the device.
Be sure you back up any data you want to keep, to a computer or cloud account, before doing the reset.
To "Hard Reset" the tablet...
1. Make sure that the tablet is actually powered off.
2. Press the "Power" and the "Volume Up" buttons, together, until you see the start-up logo on the screen.
3. Once you can see the logo, release the buttons and allow the device to enter the "System Recovery Mode".
4. Next use "Volume Down" button to get to the "wipe data/factory reset" option When in recovery mode the "Volume Up" and "Volume Down" buttons are how to can navigate and highlight what option you need.
5. Once you have selected the "wipe data/factory reset", press the "Power" button to select that option.
6. On the following screen, repeatedly press the "Volume Down" button until the "Yes - delete all user data" option is what is selected.
7. Then press the "Power" button to hard reset the tablet.