Hi there Chris and welcome
Can you tell me please the issues that your having with the trackpad and keyboard?
Thanks for that Chris, and yes, issues like this can occur at times following an update, so we will go though a number of remedies.
As the first step
Tell me how it then operates please
Thanks, ***** ***** then attempt this please
Power off the mac
Then start the Mac and hold down the Command and R keys at startup.
Hold these keys until the Apple logo appears. After your computer finishes starting up, you should see a desktop with an OS X menu bar and an OS X Utilities window
choose Disk Utility from the Utilities window, or from the Installer menu if you're started from an installation disc.
Click the First Aid tab.
Click the disclosure triangle to the left of the hard drive icon to display the names of your hard disk volumes and partitions.
Select your Startup Disk (usually named "Macintosh HD").
Click Repair. Disk Utility checks and repairs the disk.
Let this complete and when it has, tell me if you still have the problem please.
Yes there is, but there is no need for this, and I work online here as its too hard to convey specific instructions to most people over the phone.
Can you do the last instructions I gave please, and let me know the results
No there is not sorry.
Power off the Mac,
Then hold SHIFT and keep it held and power it on which enters safe mode.
Tell me how it then functions please.
ok sorry I did not see any of this in what you already tried when making the question
Then you will need to get an external keyboard and mouse and then your best to try to restore the time machines backup, it should function via an external keyboard and mouse.
Let me know the results please.
The boot mode is only the hard disk repair method we tried, its also where you reinstall, and if you cannot do anything there, then your really out of options.
USB keyboards and mouse should work, even a windows one, but if you do not have one, your likely best to go to a mac store, or a computer store and ask to test one first, just to make sure, as I would not want you to invest in one if it will not work due to this issue (which would then result in you returning the Mac to the Apple store as they would need to reimage the disk via another computer).