iPhone 5 no longer responding to touch

My iPhone 5 touchscreen is not responding to touch! Last night, my phone was working just fine. I plugged it in overnight to charge, and when I checked my phone this morning, the touchscreen had broken. Here's what's going wrong now: - The touchscreen isn't responding (I can't slide to unlock), though the screen *is* on. - There are a bunch of lines on the screen, which disappear after the phone stays on for a few seconds or when I click the sleep/wake button. The power button and home button are working as they should, I just can't get past the lock screen because I can't swipe to unlock (it's not registering the swipe or any taps). What can I do to fix this?