i had this also. I was told by apple support to update Itunes, after some diliberation i did so, even though i hate changing things on my laptop.
this made my now bricked 9.3 updated ipad 2 unrecongnisable by my laptop, yes it connected but could not be seen by itunes.
the remedy was to completely uninstall Itunes and all its components,as on this link and then reinstall the latest version
Remove and reinstall iTunes and related software components for Windows 7 and later - Apple Support
my system now recognises my bricked Ipad 2, where i go from here i don't know, Apple support have ceased contacting me on Twitter.
this has taught me two things today
1) never update straight away even if you see an update working on another device
2) always back up before updating IOS, no matter what.