I'm going to have to assume you either mis-stated the question or are making a joke. Land Rovers are ALL full-time 4 wheel drive. there is no 2 wheel drive mode. Or did you mean that it was stuck in differential lock mode?
The 4 wheel drive system on a 2002 Land Rover Discovery is engaged by pressing the 4 wheel drive button on the dash. It sends an electrical signal which activates the system.
The 2002 Land-Rover Range-Rover has four wheel drive.
The 2001 Land-Rover Range-Rover has four wheel drive.
The 2010 Land-Rover Range-Rover has four wheel drive.
The 2014 Land-Rover Range-Rover has four wheel drive.
The 2009 Land-Rover Range-Rover has four wheel drive.
The 2004 Land-Rover Range-Rover has four wheel drive.
The 2013 Land-Rover Range-Rover has four wheel drive.
The 2003 Land-Rover Range-Rover has four wheel drive.
The 2012 Land-Rover Range-Rover has four wheel drive.
The 2011 Land-Rover Range-Rover has four wheel drive.
The 2005 Land-Rover Range-Rover has four wheel drive.