Averatec Laptop computer-

This could be a simple glitch, but most likely the screen is going out and will need replaced. Start by adjusting the screen resolution in the display properties. Adjust it to a lower setting, apply, then adjust it back to where it was, and apply. If this doesn't work, then try uninstalling the video drivers from the device manager and rebooting. The machine will automatically find the video and reinstall the drivers. By doing these two, you have just ruled out a software glitch and narrowed it down to hardware, so, if the problem persists, then it's the screen and will need replacing.