Can software cause the home button to stop working on iOS? I have a new (2 months) iPhone 5 and it just froze in the "settings" app. Everything on the phone is controlled with the round button at the bottom, when I press it nothing happens anymore. 

Can this be a software problem?
Apple has a Support document describing ways to reset/restart an iPhone:

Restarting your device

Press and hold the Sleep/Wake button for a few seconds until the red &quot;slide to power off&quot; slider appears, and then slide the slider.
Press and hold the Sleep/Wake button until the Apple logo appears.

Resetting your device
Note: Reset your device only if you are unable to restart it.

Press and hold the Sleep/Wake button and the Home button together for at least ten seconds, until the Apple logo appears.