Q: Does anyone know why my 5c has black and white vertical lines on the screen, it hasn't been dropped or got wet either

hi does anyone know why these lines have appeared on my 5c it hasn't been dropped or got wet , the lines appeared when sending a text and is now the only thing you can see on the screen , the phone still rings and I can answer it ( by guessing where to swipe to accept ) , the phone is actually only 4 months old , thank you for your help