Hi 771neil,
Welcome to the HP forums!
I see you have an Officejet 6500A that all of a sudden you are unable to scan with. I'm sorry to hear this, but I will definitely do my best to assist you!
I will recommend, if you're using Windows, that you download and run the HP Print and Scan Doctor and follow whatever suggestions it presents you with.
If that doesn't help, or you're not using Windows, can you please let me know which version of Windows or Mac that you're working with and we will go from there :)