Apple - How I can get OSX to recognize Canon MP560 Scanner again?

Canon has updated most of their software (Easy-PhotoPrintEX, MP Navigator) and their drivers (printer, scanner) around the time when Lion came out. Make sure that you have the latest drivers installed.

You can download all the Canon software for your MP560 Scanner here.

Also, be sure to connect your printer via cable in order to use it as a scanner:

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Have you tried deleting the .plists associated with the printer? These are all in my ~/Library/Preferences list. I would move them to the desktop (just in case you want to move them back), restart your Mac, and try adding the printer again.