Cold reset is resetting printer to the factory default setting. Any setting at ehe printer control panel will be reset to factory default setting. A cold reset does not clear the values in the service menu, such as the serial number and the page counts.
How to Perform a Cold Reset HP LaserJet 4345 MFP

* Turn the HP LaserJet 4345 MFP off and then on.
* When the memory count appears on the control-panel display, press and hold 6 until all three LEDs flash once and then stay on. This might take up to 20 seconds.
* Press 3 four times until COLD RESET appears on the control-panel display.
* Press 6 one time. The HP LaserJet 4345 MFP should continue its initialization sequence.

CAUTION:
By performing cold reset all setting on the HP LaserJet 4345 MFP are also reset. Before performing cold reset be sure to print a configuration pada and menu map.