The only way this could happen is if the lock itself has failed or the linkage has fallen off.

You will need to remove the door panel to check, and at least that's fairly easy.

This has been posted before, but I will give you a quick rundown if you need it.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!