Q: itunes does not recognise my iphone 6s plus

See this support document for troubleshooting. If iTunes doesn't recognize your iPhone, iPad, or iPod - Apple Support

What version of iTunes is installed on your PC?

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. If you don't hear a noise suspect a damaged cable.

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

Same problem with my itunes not recognizing my ipod touch! Am I ever regretting getting a ipod because of all the crap I have had to go through and the problem is not being resolved no matter what is being done and the worst part is that I am not even allowed to call apple support unless I have my ipod serial number which is irrelevant because this is a itunes issue. They are going to be losing me as a customer and fan, I already wasted over 400.00 on a ipod touch and only got to use it for 2 months before all this crap kept happening. I have occasionally had this problem in the past and was able to fix it but, this time it is permanent apparently. I hope if enough people complain and threaten to leave itunes and apple behind and if they were to lose enough costumers maybe that will motivate them into taking this more seriously and do something about fixing this problem!

So, since you are placing all of this blame on Apple, have you made contact with them to resolve your problem? Have you tried any of the troubleshooting steps provided in this thread? My guess is you are using a Windows computer? It does not take much to fix the issue, as long as you take the time and effort to work on it.

Yes I finally got in contact with apple and I am in a much better mood now. Yes the problem is fixed now but, it took a long time to figure out how to resolve the issue because apparently it was complicated but, I am happy it is resolved! I have done about 10 or so different things to try resolving the problem but, nothing worked and now I finally have the solution should this problem ever occur again!

I understand your frustration. Now I'm going to ask you something else. Since many other people like you search this forum for answers to their questions, how about if you share what it was that you had to do in order to get resolution for your problem. It could possibly help someone in a similar predicament, and you would reduce their frustration level tremendously.