Unresponsive Touch Screen

Back in April my phone's screen randomly blacked out. I took it into apple and payed to have it fixed. They told me it was not water or drop damage, just a problem with the phone. So, they replaced the entire front panel. 8 months later, I'm driving to the airport and my touch screen stops working. I didn't drop the phone or get water on it - one second it was working and the next it wasn't. All the buttons work perfectly and the screen appears to be just fine. I plugged the phone into my mac and tried to update the phone which didn't work. I then factory reset it in hopes of it working but the screen still won't respond. Yes, I have tried tapping the corners, turning it on and off, updating, factory reset, cooling the phone down, heating it up. I'm out of options and out of a phone for my two week vacation out of the country. Any ideas?