There have ben a very small number of reports of trackpads becoming unresponsive or not scrolling after upgrading to the new Mac OS, Sierra. If you are in this group, here is a way to fix it.
Go into System Preferences, and choose Users & Groups
At the bottom left, click the lock and use your username and password to unlock it.
Just above the lock is a small "+"; click that and create a new user - can be standard or admin.
Once you have done that log out and log into the new account. If your trackpad is functioning normally you can try the Fix. If not, you may need a hardware repair - please put in a help ticket in that case.
Second, the Fix. (if you find this too advanced, pease put in a help ticket- it's OK!)
In Finder, click on the Go menu while holding down the option key - this will allow you to select your hidden Library Folder.
Next, open the Preferences folder, choose and copy the 2 Multitouch preference lists:
For ease, I move these files to the Users/Shared Folder
Now logout of this account and back into yours.
Use the "Fix" instructions to find Library/Preferences in your account, and once you have, copy the 2 preference lists from the Shared folder into your Preference folder.
When you are asked if you want to replace the current files, click yes.
Now, restart, log in and your track pad will be fixed!