||For HP printer offline fix follow below mention method:
•Turn on the computer to which the HP printer is linked. The printer does not have to be turned on in order to switch it from offline to online.
•Tap once on the Start menu.
•Tap "Devices and Printers."
•Tap the icon for the HP printer you wish to use. Where the status shows "Offline," click the word "Offline" and then hit the "Printer" option on the pop-up window that results. Uncheck the "Use Printer Offline" option
If follow mention point if you are unable to fix the error then you can take support from HP support team. The experienced Support team is resolving your problem as soon as possible.for more info visit here: https://www.hpprintersupportpro.us/blog/fix-hp-printer-offline-issue/