There could be many valid grounds that result in turning canon printer offline. To fix the issue, try to restart your printer by turning the power off and back on, restart your printer spooler service from printer properties, check if the printer is set as ‘Use Printer Offline’; disable it, clear the printing jobs in the queue. Uninstall and reinstall the driver from your system and setup canon printer again from scratch or call Canon Printer Customer Service USA/Canada: +1-855-869-7373, UK: +44 800-041-8324