Restart the device. Sometimes this is all it needs.
1. On the home screen, "Swipe" down the "Notification Bar" at the top of the screen.
2. Tap “Screen rotation” to turn it off/on.
If you don’t see, “Screen rotation” when you go into the "Notification Bar", you may have to swipe "Left" on the selections. You can also tap the "Edit" button at the upper right corner to add the button.
Some tablets may have the option under “Settings”, then “Display” and finally “Screen rotation“.
1. From the home screen, tap and hold the "Notification Bar" at the top of the screen.
2. While holding the screen, swipe downward.
3. Here you can now tap “Orientation Lock“. When it is on, the green indicator will be lit. The screen will lock in the position you currently have it at. When it is disabled, the screen will rotate normally.
If the three prior options don't work for you, try removing the battery while the device is still on, leave it out for a few minutes, and then replace it.
If none of the above work, you may need to do a full "Hard Reset" of the device. This should always be a last ditch option.
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 phone...
1. Make sure that the phone 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 phone.