Q: i cant touch my screen in iphone 6, what i need to do

try restart

Restart your iPhone, iPad, or iPod touch - Apple Support

If your device is frozen then you will want to follow this: If your iPhone, iPad, or iPod touch doesn't respond or doesn't turn on - Apple Support

~ Also remember to force close all applications if or when the device restarts: Force an app to close in iOS - Apple Support

~ If this doesn't work then you would want to follow this article: If the screen on your iPhone, iPad, or iPod touch doesn't respond to touch - Apple Support 

Best of luck and if all else fails you could simply do a backup and then restore your device as new to assure it's not a software issue using the following articles:

How to back up your devices using iCloud or iTunes - Apple Support

Use iTunes to restore your iPhone, iPad, or iPod to factory settings - Apple Support

Download past purchases from iTunes - Apple Support

Hi

Try a Reboot press & hold power button & menu button

Hold both down until you see Apple Logo .

You will not lose any data .

Cheers

Brian uk