If you are facing an HP Printer Offline situation then you can download the HP Print and scan doctor from the website and diagnose the problem in some simple steps. You might see printer updates during the scan, ensure to install them. Restart your system and this should solve your problem of HP printer going offline.
If you have a number of printers associated with your system then make sure that the printer that you are trying to print from is selected. Set the preferred printer as default and you will be able to print again without facing the HP printer offline issue.