iTunes no longer recognising any devices

Hi,

Decided to try and update to iOS 7 today so plugged my iPhone 5 into my Windows 8 laptop to back it up before installing, but was told I can't without updating iTunes first. Updated iTunes successfully but now it doesn't recognise either my iPhone or my iPad, although Windows recognises both. I have tried:

- turning the iPhone/iPad on and off

- turning my laptop on and off

- uninstalling and reinstalling iTunes

- using different USB cables

- stopping the iPod Service and restarting it

- deleting the temp folder and restarting

I've not installed anything else today, so how it could go from recognising my iPhone and then not within the space of 5 minutes is beyond me.

Anyone have any ideas?