My touchscreen lost functionality gradually over the second year of use. (HP Officejet 6500A). It's now 5 years old.
Also my USB printer cable broke years ago, which forced me us it as a network printer via ethernet cable, and scan using the HP Webscan page (http://10.0.0.x), where "x" is the last digit of the printer IP Address. (Check "Devices and Printers" to get this as mine changes dynamically)
This means I can use the printer / scanner option without needing to use the faulty touchpad.
If you are ever reset your printer (like me), and get stuck on "language selection" or something else where input from the touchpad is required, you can put it into "Store Display" mode by doing the following:
Switch off printer. Then hold down power button until green LED at bottom left lights up. You're now in a diagnostic mode.
Home, Back, Home Home See https://www.youtube.com/watch?v=o--DFGMeyYQ for a funny demo where a guy reflashed his printer. Note, I have not reflashed, so I don't know what it does.
I tried doing all resets (semi,partial, out of box, full), but they all led me back to language selection (which I couldn't select due to faulty touchpad), hence my Officejet was useless at this point.
Then I tried MFG which allowed me to (somehow) get it into "Store Display" mode or something alike when it restarted. This defaulted the language to English and hey presto, I can print and scan again using the network with the touchscreen stuck on something or the other. But it works!
I hope this helps you, I can milk some further use out of this printer/ scanner yet!