MacAir book laptop screen black with 2 coloured lines down the right hand side

try connecting an external display or TV set. If you get ANY coherent picture, it is working as designed, and readers can help you make further progress.

vertical lines do not bode well for the health of your built-in display. Only the display assembly itself knows anything about Vertical. Display scan lines are created, stored, and transmitted as stacked ROWs.

<< I can’t plug my mac air laptop into my television as I don’t have the right cables. >>

You appear to be understanding me perfectly. Your choices now are:

• get the required USB-C to HDMI cable/adapter to use with your TV set or a display

• make an appointment at an Apple-owned store for a free evaluation

• make an appointment an An Apple Authorized Service Provider, and pay the evaluation fee.