Here is what worked on an identical printer. Not sure if you are up to it. Better than pulling your hair out!!
*** Fix your HP Photosmart Printer (Reset Code/Master Reset) ***
Also, if you would rather do software stuff first, download the drivers and reinstall them. The ones that come with it are always outdated...
you didnt say if it was XP or vista, so pick your proper download...
Pick full feature software. (or basic scan and driver if you never installed the whole software originally)
Best of luck! It worked before (the reset)