It’s possible that you may have dead pixels or lines on your laptop display. To investigate the cause of these lines and rectify it, you may take the following steps:

1. Check for magnetic influence from a speaker or other device. Make sure to move any objects which may be producing a magnetic field close to your laptop.
2. Look into the display settings of the laptop. Some lines can be caused by incorrect display settings such as low or wrong resolution.
3. Verify if the lines are only visible in certain applications, or in all applications in which case it may be a display issue.
4. Look for any hardware issue such as loose cables or connections. Verify if the lines appear on an external display as well.
5. Try a restart of the laptop or a driver update.