I suspect that it might be a problem with the iPhone, as you likely got the iOS 6 update. I don't have much to suggest other than checking another mass storage device to ensure it is a problem with the iPhone.
I'm running Windows 7 on a Samsung x460 laptop, and just recently I can't get my iPhone to be recognized anymore, by iTunes and by the computer's OS.
When I plug in the iPhone with a USB cable, the OS's alert of a new external drive being plugged in sounds off, but then there seems to be no further change - nothing in the Computer system shows up,
I've tried looking in the Window's application "Computer Management" -> Storage -> Disk Management, to see if the iphone is 'there' but unlabeled, but it does not show up at all.
I've also tried wirelessly syncing the iPhone through iTunes, but cannot get the computer to recognize the phone. The iPhone sees the computer, but the option to "Sync Now" remains blocked.
What can I do to sync my iPhone, and to get the computer to recognize it again? It's very important for my work to have podcasts and audio lessons ready to go, so right now I'm stuck!