Turning the power ON/OFF while the print monitor screen is displayed may cause the printer driver to go off-line and make printing impossible.

In this case, open the [Printers / Printers and Faxes] folder of your Windows computer to check if the printer driver is off-line.
If the printer driver is off-line, close the print monitor screen and turn the printer's power ON/OFF a few times. If the printer driver remains off-line, restart the computer.