The most obvious cause of HP printer being offline is that it is set to offline mode in settings. This is how to change HP printer from offline to online. Click on the start button and go to the printer control panel. Then, click on devices and printers. Make a right-click and select, see what’s printing. You will be directed to another window where you have to select printer option from the menu. Then, a drop-down menu will appear, and select, use printer online from there. Find more email issues at contactforhelp.