iphone 6 screen frozen on plug into itunes and now my laptop isnt recognising the device so I cant restore

I tried to install the new iOS9 software onto my iPhone 6 but half way through my laptop didn't recognise the device! I tried shutting down the laptop and troubleshooting the device but nothing is working! The thing I am most worried about is my iPhone screen is frozen on the plug into iTunes icon and wont allow me back into my phone. Can anyone please help me?!