iPhone 6 Plus screen suddenly became completely unresponsive
This morning when I used my iPhone it was fine; this afternoon, suddenly the screen has become completely unresponsive to touch, and now the phone is completely unusable. Several restarts have not solved it, though for awhile they restored functionality briefly. Not any more. I can turn on the power and the home button works to get me to the keypad screen for my passcode, but that's it.
I have an iPhone 6 Plus with the latest iOS update. I wasn't even using the phone at the time. This morning it worked, this afternoon it didn't. I have been organizing and updating my Photos and iTunes libraries and I bought iTunes Match, but I did all that work on my Macbook Pro and merely let iCloud do its work to synchronize it with my iPhone. Could that be related? The phone died while iTunes Match was uploading CDs (which went fine BTW). Fortunately I was able to sync and back up the iPhone through iTunes while it still worked occasionally, because now iTunes does not recognize the phone because it's locked, and as I said, can get to the keypad but not actually type on it to unlock it.
Anyhow, it's completely unusable at the moment. Help please?
MacBook Pro (Retina, 13-inch, Mid 2014), OS X Mavericks (10.9.5)