Maybe a bad app is the reason for touch screen issues. If it drains your device's resources, it won't work normally. To resolve this, you need to find and uninstall the bad app or apps.
See the don't know how to uninstall a program / an app guide if you are not sure how to remove apps.
If you have an iPhone 6s or later and it isn't responding properly to 3D Touch gestures, you need to adjust the settings:
Maybe your device froze due to a software conflict. All you have to do is to restart your device.
In order to restart your device, press and hold the Power ON/OFF (Sleep/Wake) button until a slider appears and move the slider to the right to power off the device.
Press and hold the Power ON/OFF (Sleep/Wake) button again after 10-15 seconds, to turn on the device.
Note: You can also perform a force-restart, by pressing and holding the Home and the Power ON/OFF buttons.
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