Hi there. . My name is***** am a computer professional with over 15 years of experience with both Mac and Windows computers, phones, tablets, and printers. It would be my pleasure to assist you with this. Can you tell me what operating system is on your computer?
If you're not sure, you should be able to use one of these links to find out. Or, if you prefer I can connect to you remotely and work on this while you watch.
Can you click this link and tell me what you see please?
From the Apple menu, choose About This Mac. Your version of OS X appears directly below “OS X
Once I know the operating system I should be able to walk you through the necessary steps to troubleshoot the printer. You mentioned that you had tried shutting down the printer, however, it's a good idea to shut down both the printer and the computer at the same time. Please try that and see if it helps. Also, can you let me know whether the error message appears on the printer itself or in the computer screen?