From Canon Support Website (Direct link does not work, type reset and look at top option).
Solution: Setting the MP980 back to default settings
Instructions to change the machine back to its default settings.
1- Press the <HOME>
button.
2- Use the Easy-Scroll Wheel or the right / left arrow to select [Settings], then press the <OK>
button.
3- Use the Easy-Scroll Wheel or the right / left arrow to select [Device settings], then press the <OK>
button.
4- Use the Easy-Scroll Wheel or the up / down arrow to select [Reset settings], then press the <OK>
button.
5- Use the Easy-Scroll wheel or the up / down arrow to select [Yes] on the confirmation screen and then press <OK>
.
6- Press the <HOME>
button to return to the HOME menu.
Note: Changes the settings back to the default (factory settings), except for the language for LCD messages and the position of the print head.