Hello,
Here is the HP troubleshooting link for the 7000 series printers 'Out of Paper' Error Message and the Printer Does Not Pick Up or Feed Paper, and a short video about it.
http://h10025.www1.hp.com/ewfrf/wc/document?docname=c02034665&cc=us&dlc=en&lc=en&jumpid=reg_R1002_USEN