Q: iOS 931 iPhone 5 undiscovered on iTunes. Am I the only one?

Are you using a Mac or PC ??

It may not just be a matter of iTunes being up to date but your operating system.

Following are the requirements for iPhone 5 for iTunes.   iPhone 5 - Technical Specifications

• Syncing with iTunes on a Mac or PC requires:
  • Mac: OS X v10.6.8 or later
  • PC: Windows 7; Windows Vista; or Windows XP Home or Professional with Service Pack 3 or later
  • iTunes 10.7 or later (free download from here >  Get the latest version of iTunes

See this:  iOS: Device not recognized in iTunes for Windows

You are not the only one, others have reported the issue as well. If you are running Windows 7 or above you should be able to download iTunes 12.3.3, the latest version.

Some have had to delete the Apple Mobile Device driver (it re-installs on the next pc boot and device connection). Some have had to disable their antivirus, particularly McAfee as is known to create issues with iTunes. For the driver see the article below.  While the article refers to W10, the W7 process is nearly identical. Please note that this forum is having issues with links today. If unable to open directly from below, paste the link to a browser and open it there.

http://www.technipages.com/itunes-fix-iphone-or-ipod-not-detected-in-windows

Most are not having issues with iTunes for Windows and I have not heard of any bugs.

Try uninstalling iTunes, rebooting your PC, and reinstalling it again. Also disable the Antivirus temporarily while you are downloading the iTunes files and installing them.

See this ASC User provided tip for issues with iTunes and Windows. You can find information on removing and reinstalling iTunes to help you with the recognition issue. This is probably the most comprehensive collection of tips for iTunes and Windows. Troubleshooting issues with iTunes for Windows updates

tt2, the chap in London that wrote the User Tip, is the top expert on iTunes here and a very nice person to boot. I have relied on him and emailed him a bunch of times, always helpful, always courteous. 

Be careful with an older version of iTunes, as it may prove to be a problem with syncing with iOS 9.3.1. You will have to update soon enough. I suggest you work out the issue you are experiencing now, before something occurs that causes you more grief later.