Hello CVinh,
Thanks for using Apple Support Communities.
If your iPhone's screen is unresponsive, then please reset your iPhone by following the directions below.
First, try to force your device to restart.
- Forcing your device to restart won't erase the content currently on your device.
- You can force your device to restart even if your screen is black or your buttons aren't responding.
Press and hold the Sleep/Wake and Home buttons at the same time for at least 10 seconds until you see the Apple logo.
If your iPhone, iPad, or iPod touch doesn't respond or doesn't turn on - Apple Support
Have a good one,
Alex H.