Ensure that there's A4 paper in the printer.
Click the HP Printer icon on your desktop. (If the icon's not there you can also go via Start > Programs > HP > HP Deskjet 3050A J611 series > HP Deskjet 3050A J611 series).
Click Printer Actions and then click Maintenance Tasks to access the Printer Toolbox.
Click Clean Ink Cartridges on the Device Services tab. Follow the onscreen instructions.
Information sourced from . . .
http://h10032.www1.hp.com/ctg/Manual/c02853536