My MacBook Air has a white screen with colored lines

I was doing homework on my Mac and I went to go grab some food and it went to sleep. I had my iPhone charger plugged in but my phone was not attached. When I unplugged the charger and handed the Mac to my boyfriend, the screen looked white with colored lines running through it. There was nothing wrong with it before this and it was not damaged (stepped on or hit). How can I fix it ?