For switching HP printer from offline to online, click on “start” then from the list that appears select “devices and printers” folder then click on your HP printer icon, after that click on the option “printer” and from the menu that appears uncheck the option “use printer offline” your HP printer will be back to the online status also ensure that there is no paper jam in the machine also there should be no hardware issue. If you are still not able to get your printer back to online then connect with the experts at HP printer contact number uk.