HP.com/Support>HP Deskjet 3845 Color Inkjet Printer>Drivers & Software Downloads>Pick your Operating System,
You didn't state what Operating System you are using. I'm going to pick Vista to use as an example,
There is no full feature software and driver package for Vista. However there is a basic driver, and a workaround. Here, http://h10025.www1.hp.com/ewfrf/wc/document?docname=c01655752&lc=en&dlc=en&cc=us&product=372330&os=2093&lang=en
If you have Windows XP, here is the driver, and the HP Essential software,
First download the driver, (IN DOING all of this, DO NOT have the printer plugged into the computer, and have the printer turned off)
Click on ->
HP Deskjet Full Feature software/driver: USB cable
(Size is 14.41MB)
It will go to your desktop screen. Double-click on it. If a window comes up that states Extraction Wizard, go up to the top right, and click on -> Extract All Files. Follow the instructions. Look for a file that has -> Setup, or a file that ends in -> .exe
It may ask you if you want to restart your computer at this time.
NO! Not yet!
Now download this for the same page as above,
HP Photosmart Essential Software for Photo Editing, Printing, and Sharing
(Size is 6.19MB)
Follow the same instructions as I gave above.
Would appreciate a follow up to see if this 'cured' your problem.
Have a nice day.