If you Dell laptop computer screen isn't displaying a full-screen image after you adjust its overall resolution, this means that you've changed to a resolution that your monitor doesn't support. You've either picked a resolution that is too large or too small for your laptop's built-in screen to handle. You can correct this by switching it back to its recommended resolution, using native Windows tools.
Right-click on your Dell laptop desktop.
Select "Screen Resolution."
Choose the "Resolution" drop-down menu.
Slide the vertical bar to the resolution with the word "Recommended" listed next to it.
Select "Apply," then click "OK."