Re: Samsung Galaxy 5 touchscreen doesn't work after software update
You can remove the battery to power off your phone to see if that clears up the issue for you. If the issue persists, you can do a hardware factory data reset on your phone. This will delete everything stored on your phone's internal storage and reset your phone to the factory state. The recent update will still be there, however.
I could only find written instructions from another carrier's website, but it will apply to your phone, as well. See the link below: