This blog entry I update periodically when I run into problems getting my printer to work with whatever version of Ubuntu I'm using (I've been using Ubuntu since its version 6.) For Ubuntu 14.04, these simple instructions from July 2008 allowed my printer to start working again, and what I might recommend first if you're having problems getting your printer to work with Ubuntu. It's hit or miss, however, and sometimes turning the printer on at the same time the printer detection is occurring helps Ubuntu find the printer.
Alternatively, what has worked for me in the past was going to HP's Linux Imaging and Printing site and doing a manual installation of their latest version. After entering various O/S and printer model information I was given Installer instructions to follow. During the installation process I chose the option to uninstall the hplip already on the machine and do a new installation, rather than just an overwrite.