If you have a computer that uses a removable keyboard, reseating it for just a few seconds could be the fix. Close and reopen your laptop slowly. Examine when the lines appear on the screen as you ...

Restart your computer to initiate the clean boot ... Dealing with horizontal lines on your HP laptop screen can range from simple fixes like adjusting screen resolution to more complex hardware ...

you might have enabled the greyscale filter on your computer accidentally. Check this in Settings and disable the greyscale color filter. Read next: Horizontal or Vertical lines on Laptop screen ...