Many of the error messages that appear on a Canon MP260 printer can be cleared by using the red "stop / reset" button. This is especially true for the messages you receive when at least one of the ink cartridges are empty.
If the printer displays that an ink cartridge is empty, simply press and hold the red "stop / reset" button on the printer for five seconds. The printer should continue printing, and use any of the remaining ink in the cartridge.
If the printer thinks that both cartridges are empty, you will receive a second error message, and you will need to hold the button for another five seconds.
If the copper circuitry on the cartridges are actually damaged, unfortunately, this process will not work.