itunes is unresponsive to my iphone since the update

Are you using a Mac or PC?

Please test after taking each of the steps below that you haven't already tried. Back up all data before making any changes.

1. Follow the directions in this support article.

2. If you subscribe to iTunes Match, then on the device select

Settings ▹ iTunes & App Store ▹ iTunes Match: Off

and try again. Re-enable iTunes Match if the sync succeeds. (Credit for this solution to ASC member Blue Velvet.)

3. Skip this step if you're not running OS X 10.9 ("Mavericks") or later. It moves to the Trash "semaphore" files that have not been cleaned up by the system and may be interfering with normal operation. The files are empty; they contain no data.

Please triple-click anywhere in the line below on this page to select it:

find L*/{Con*/*/Data/L*/,}Pref* -type f -size 0c -name *.plist.??????? -exec mv {} .Trash/ \; 2>&-

Copy the selected text to the Clipboard by pressing the key combination command-C.

Launch the built-in Terminal application in any of the following ways:

☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)

☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.

☞ Open LaunchPad and start typing the name.

Paste into the Terminal window by pressing the key combination command-V. I've tested these instructions only with the Safari web browser. If you use another browser, you may have to press the return key after pasting.

Wait for a new line ending in a dollar sign ($) to appear below what you entered.

Log out or restart the computer and empty the Trash.

4. As a last resort, restore the device in recovery mode.

If your iOS device isn't showing in iTunes try the following:

1. Open Control Panel > Device Manager
2. Plug in your device
3. Locate Universal Serial Bus Controllers > Apple Mobile Device USB Driver.
   It is also possible the device may show under Imaging Devices, Portable Devices or Other Devices or as an MTB USB Device.
   
4. Right-click and select Update Driver Software...
5. Click Browse my computer for driver software
6. Browse to C:\Program Files\Common Files\Apple\Mobile Device Support\Drivers or
   C:\Program Files (x86)\Common Files\Apple\Mobile Device Support\Drivers
7. Click Let me pick from a list of device drivers on my computer
8. Click Apple Mobile Device USB Driver
9. Click Next, then Close and exit Device Manager

For step 3 above, open the device manager. Expand any of these sections that are listed.

• Universal Serial Bus Controllers
• Imaging Devices
• Portable Devices
• Other Devices

Connect the device. You should hear the telltale sound of Windows device connection and one section should gain a new entry. That should be your device. It may not be labelled correctly at this stage.

Or try If iTunes doesn‘t recognize your iPhone, iPad, or iPod - Apple Support

Failing that try a full tear down and rebuild of iTunes as set out in Troubleshooting issues with iTunes for Windows updates.

Or lastly try rolling back to the last build of iTunes that worked for you. See iTunes installers for download links. If you're rolling back from 12.3.3.17 to 12.3.2.35, for example, then you'll also need to roll back the database in the way described in Empty/corrupt iTunes library after upgrade/crash. The tip includes suggestions for reintroducing any recent purchases so at worst you lose a few playcounts and/or a recently created playlist.

tt2