Have you tried closing the Phone (and Contacts app, if that's open too)? What about restarting the phone?
Hi
I have iPhone 5 purchased 3 years back in US and I am now in India.
So, I couldn't get it repaired for lock button issue thru Apple India Support as well.
Next, I upgraded to iOS 9 recently and started facing issue. Touch screen occasionally stops working.
I must wait for whole battery to get drained. I couldn't find any other option to turn the phone off. Is it issue with iOS 9? Please let me know how to turn off and turn on my iPhone immediately. Any help is greatly appreciated.