Itunes not recognising any devices

Hi,

I have imac running 10.12.6 MacOS Sierra,

itunes 12.8.0.150 - updated 14 July

I have iphone 7plus 11.4.1

Just this week soon after updating to 11.4.1 which was actually around the same time as the itunes update also - my device just will not appear in itunes.

Normally I would open itunes and connect my iphone using cable and the device would appear. Now nothing, I've tried closing down itunes and reopening. Tried hard reset on iphone 7 plus and again no joy.

Really don't no what to do as the only thing that have changed have been apple os updates.

Any help much appreciated

Shane