3D touch not working on iphone 7 plus

You could try a force restart of your iPhone using the steps below.( a force restart will not delete any settings or data )

• On an iPhone 7 or iPhone 7 Plus: Press and hold both the Sleep/Wake and Volume Down buttons for at least ten seconds, until you see the Apple logo.
• On an iPhone 6s and earlier, iPad, or iPod touch: Press and hold both the Sleep/Wake and Home buttons for at least ten seconds, until you see the Apple logo.

Then wait for the iPhone to reboot and go ahead and make sure the iPhone 3D Touch is enabled and test it.

If you still have a issue it might be worth visiting a Apple Store or by calling Apple Support and have a chat with them to see if they can assist further.

Contact Apple for support and service - Apple Support

You could try making sure it is enabled and or adjusting the sensitivity of the 3D Touch in the Settings on your iPhone using the information in the Apple Support link below.

Change 3D Touch sensitivity on your iPhone 6s, iPhone 6s Plus, iPhone 7, or iPhone 7 Plus - Apple Support

No worries I am glad I could help.