HP DJ2131 Printer Offline
Remove the USB cable from the Mac computer, and then reconnect it.
Turn off the printer, and wait for at least 5 seconds.
Remove the USB cable at the back of the printer, and turn it on .
Wait until the printer becomes silent. Reconnect the USB cable to the printer after 5 seconds.
Open the Printers and Scanners option from the Mac computer. To check the network connection of the printer in the Open Print Queue.
Disconnect the power cord from the rear of the printer to reset it.
Wait for about 60 seconds, and reconnect the power cord to check whether the issue is resolved.
Search for Print, and select Printers and Scanners. Select your HP printer name and click the Default Printer option.
Select your printer name from the list and click the ‘-’ symbol to delete it.
Click the Add button to add the printer to the computer. Select the Print Using or Use option.
Select your printer name or simply click the AirPrint option.
Right-click on the blank space in the list, and select Reset Printing System.
Select the Reset button, and then enter the admin user name and password.
Wait until the computer resets the printing system and add your HP printer as mentioned above.