Q: My iPhone screen is frozen with the apple icon.  I cannot power down or do anything.

I plugged my iPhone in to charge it.  I unplugged it and the screen was frozen (black with white apple icon).  I cannot power down or use the touchscreen.  The phone seems to be working because the alarm I set went off and Suri was activated when I was trying to power down and restart. How can I get back to my touch screen?