Hi MR0,
Welcome to the HP Forums, I hope you enjoy your experience! To help you get the most out of the HP Forums I would like to direct your attention to the HP Forums Guide First Time Here? Learn How to Post and More.
Sorry to hear that you are having issues with the printer not scanning. I have had this issue myself and I was able to resolve the issue by doing a complete uninstall and then a reinstall. Please click on the following link for the HP Photosmart C3100/C4100 All-in-One Printer series Full Feature Software and Driver.
If you are still having issues, please feel free to write back.
Thank you for your time.