Please try this, as I also faced the same problem and this fixed. Don't go to device manager directly.
For windows 7/8/10:
- open devices and printers.
- Right mouse click Ipad (or iphone) icon and select properties.
- Select properties on the hardware tab.
- Select change settings.
- Select driver tab and click on update driver.
- Select browse my computer.
- Click browse button and find C:\Program Files\Common Files\Apple\Mobile Device Support folder.
- Click next and it'll install the Apple Mobile Device USB Driver.
After this, it should show up in itunes. Unfortunately, I have to do this every time I want to sync to itunes. Hopefully, this save someone else my grief.