Why does my iPhone 4s screen show black and blue lines?

Vicky, your front display consist of multiple pieces. In your case the digitizer (glass) is still intact, but your LCD is no longer working. I suggest that you change the display assembly. Here is the guide for it. The assembly is available right here as well as many other places. Hope this helps, good luck.

"Try pressing the home and power button at the same time but holding it down until it shows the apple sign. If that doesn't work you can rest your iPhone before sending it back for a replacement.

1- Hold down the home and sleep/wake button at the same time (In order to power off that way)

2- Once you were able to power off, next hold down on the home button and at the same time plug the USB cable into the phone and computer. Keep holding the home button until a message factory settings. It will take a few minutes for it to appear.

3- Once it does click on restore."

mine has done the same thing. im really worried that it might not work anymore. ive already cried today about it. what should i do ~ Aiyana Irving

i need help to and it does not work

Dropped my iPhone today and the screen didn't break, but blue and balck vertical lines show up when i press buttons. I have a lot of important text messages and pictures that i don't want to lose. My phone is still responsive but continues to only show blue and black lines on screen. Very worried and need help!!

You should follow the screen repair guide to replace the screen.