Connect an external monitor to the laptop and check what its' display is like.
If it also has lines then there is a problem with the GPU or the motherboard or both.
If the external monitor display is OK then there is a problem with either the video cable, video cable connections at either end, (motherboard or screen) or the screen itself.
Here is a link to the service manual for your laptop. On p.37 it details the necessary pre-requisite steps and then the procedure to remove the display panel.
This will help if you need to check the video cable connections or if you have determined that the screen is faulty.
Depending on what particular display you have, you will find part numbers either on p.40 or at the top of p.37 for the screens. Your display's part number may be printed somewhere on the back of the display panel. You'll have to remove it to find out if it is ;-)
If you search online using the part number only in the browser search box, you will get results for suppliers of the part.