Q: I have tried to connect iPhone 5s via USB to my computer but it says it doesn't recognise the USB

Hi,

Disconnect the iPhone from the computer.

Restart your computer and iPhone then try again.

change the usb port or change the iphone cable

If you haven't already attempted an update to your current version of iTunes, I would start with that. http://www.apple.com/itunes/download/

If you've already installed the latest iTunes, the next step I have found through helping numerous people through this issue that the following article is the best means to resolve this.

Remove and reinstall iTunes and related software components for Windows 7 and later - Apple Support

Specifically, all steps must be completed in their exact order. Steps 5-13 under 'Make sure that iTunes and its related components are completely uninstalled' are also essential in making sure you run into no further issues of having the appropriate drivers installed. Remember to delete all previous copies of the iTunes Installer file from your computer and to download a fresh copy of iTunes through http://www.apple.com/itunes/download/