The unresponsive screen issue will be fixed as you follow the following steps below.
• Try powering it off by holding power button for 10 seconds.
• Pressed the volume + button and power button simultaneously.
• It will powered up into some restore screen then appear restore to factory settings
• Used volume buttons to scroll through the menu, then used the power button to "select" the recalibrate option, it said don`t touch the screen, took a few seconds and powered off.
• Then the screen is working again
Have you dropped the phone ?