Restart the laptop
Check if the lines appear in BIOS or startup screen
Connect an external monitor
Update or reinstall the graphics driver
Roll back the graphics driver if the issue started after an update
Adjust the screen refresh rate
Reseat the display cable if accessible
Check for loose or damaged screen cable
Inspect for physical damage to the display panel
Run a hardware diagnostics test
Remove recently installed software or updates
Boot into Safe Mode
Reset display settings
Perform a system restore
Replace the LCD screen if the panel is faulty
Replace the display cable if it is damaged
Repair or replace the graphics card or motherboard if needed