Cold reset restores all settings to factory defaults. In most cases it is used to reset the previous users' IP settings for a built-in or installed network card. However, it also resets paper size and type and similar settings, which can also be very useful.
HP 1100 - Turn the printer on. When its ready, press and hold the GO button for about 5 seconds.
HP 1200 - Turn the printer on. When its ready, press and hold the GO button for about 5 seconds.
HP 2100 - Turn it off. Press and hold CANCEL. Turn the printer on and wait for all LEDs to be on. Release the Cancel button immediately.
HP 2200 - Power off. Press and hold GO.Turn the printer on and continue to hold the GO button until the attention light comes on. Release GO and wait for the printer to reset itself
HP 2300, 2400, 4200, 4250, 4300, 4350, P4015, p4515 and many others. Turn the printer off and back on. When the memory count starts, press and hold the CHECKMARK button. When the LED lights are solid release the button. Press UP or DOWN to find the COLD RESET option. Press CHECKMARK to select it.
HP 4000, 4050, 4100, 8000 and some others. Press and hold the GO button. Turn the printer on. Release it when COLD RESET appears on screen.
HP M3035 - Turn it off and then on. When the memory count begins, press and hold the "6" button until all LEDs are on. Release it. press the "3" button and find the COLD RESET option. Press 6 to run the cold reset.