Dell 2150cn/cdn Color Laser Printer - Manual (Page 330)

328 Understanding the Printer Menus
3 Press button until Maintenance appears, and then press the (Set)
button.
4 Press button until Reset Defaults appears, and then press the
(Set) button.
5 Ensure that Are You Sure? is displayed, and then press the (Set)
button.
The printer is restarted automatically.