How to open door on2000 mercedes s 500 door deos't open from inside or outside

SOURCE: door in back cant open from outside and inside

I'm sure VW had a recall to replace door lock mechanisms around that age, check with your dealer. If the door and window on the same door are not working it could be lack of power to that door, check the wiring harness connection is still plugged in and ok on the b pillar (b pillar is the vertical panel between front and rear door), remove rubber gaitor bellows and check connections.

SOURCE: Passenger side rear door only opens from inside.

It sounds like the linkage connecting the door handle to the latch has disengaged....you'll need to remove screws that are by the door handle, arm rest, under door and side of door and then gently pull back on the panel as there will also be retaining clips attached and you don't want to break them. You'll need to lift the door panel upwards in order to get it off the window ledge. You can then pull off the weather seal in order to see the inside of the door....

SOURCE: power window open partially with inside or outside

inside the mechanical lock (The part that actualy holds the door shut when you close it) there is a switch that informs the control unit that the lock is either locked or unlocked.
These switches fail sometimes, when this happens the control unit is not aware that you have opened the door, and therefor will not wind the window down slightly.
The switch is integral with the lock unit, and they are not easy things to replace either.