I have an iPhone whose screen turns on but doesn't respond to touch. Could this be a software issue?
Solution 1:
The only software "issue" that I can think of is the guided access, which e.g. parents can use to restrict their children while using the iPhone. However, I am quiet sure that it is disabled by default, once you restart the iPhone by forced reset (press lock-button and volume-down-button simultaneously for a couple seconds).
In addition, you could delete everything and make a factory reset with iTunes. But could not help at all, if it is not a software issue.
Furthermore, the guys at the apple store are really helpful and have special tools for diagnosing problems. As far as I know, as long as they just diagnosing the problem, the consulting is free.