My screen suddenly out of nowhere polarized and changed colors... seems to be functioning otherwise...

open the screen and go to settings check there for a screen color setting

Try restarting it

Of you are referring to the background color of the home screen then just long press it {hold your finger down on an empty space) and you should get the option to set the background.

It is broken. Return it for replacement or refund. If you can't return it, you could try taking it apart and verify the ribbon cable connection the screen is secure. Otherwise replace the screen.

In the setting button go to general and after to the accessibility section in the right pane and restore the color and contrast.

Steps To Change Font Size On Nook Tablet
Step 1: Chose a book that you would like to read on your Nook.

Step 2: Next, view the Reader Settings

Step 3: Tap the screen to expose the menu, where you will see a "Text" icon.

Step 4: After having clicked on the "Text" icon, you will see that you have the option to change the font size. There will be a letter "A" that will allow you to change the size. Click on the "A" and decide which font is best for you.

Step 5: Touch the main screen to return to your book.

If you still have any kind of problem then you can take nook color support from experts by calling nook help number. You can also navigate to www Nook com for more information.

Which device?

Did you invert the colors? This is under Settings > General tab > Accessiblity. Invert Color

You can't do this unless your ipad is jail broken. The only thing you can do is invert the colour of your screen in Accessibility settings, but that's probably not what you're after.

You need to press the Function button, then the num lock button. The function button may be labeled FN or F in a different color, the same color as the num lock button.

If that doesn't work, go to start, all programs, accessories, accesibility, on screen keyboard....it will display a regular keyboard on your screen, then click on the num lock key on that keyboard.