my rear right passenger door is lock .cant open it

I have exactly same issue with my 2004 Mercedes C230 sedan on the rear right passenger door. It CAN be opened from outside (once the door is unlocked), but can NOT be opened from the inside. Originally I thought that it was a LATCH-related problem as on the rear right passenger seat we do have a car seat installed. However, I looked it up in the c230 user's manual and it did NOT mention anything about this. Any help would be highly appreciated.

Open the door from the outside, and look around the edge of the door for a "Child-Proof" lever. It can be set so a child cannot open the door from the inside. If you have the owners manual, I am sure it is covered there. Jim

If the door WON'T open then why do you suggest opening it from the outside? It won't open AT ALL.

I had the same problem with my right rear door. It wouldnt open from outside or inside. I knew the cable was attached because I could hear it moving when pulled on each handle inside and outside. I tried all the tricks that i could find on Google and nothing worked until I got wd40 and sprayed the krap around the latcj area. I used the bottle with the thin attachment nosle and got it between the door and the frame. Waited for 5 minutes and I had to shake it (almost like vibration) short pulls and back on the outside handle. Also pushed the door in a little every once in a while and do the same. After 2 minutes, the dor propped open and everything was back to normal. That was my trick and worked for me, it might work for others too. Worth to try. I didn't know what else to do so I was almost pissed off ready to pry it open and then this worked fine and got the door open. Hope it helps someone. Good luck.

Wow. I did WD40 trick. Sprayed outside through door crack up and down several locations. I approximated looking at other door jam. Didn’t work day 1. Did it again next day. Pushing locked door in to help loosen lock. Also pushed lock and unlock mechanism many times. I drove to store. When I return to car I thought I’ll try door. Made a funny click sound as I pulled lever then it opened. I sprayed WD 40 again directly in latch area to be sure before closing. It’s good now. Thanks to previous blogger note about WD40. Wow

I have an 06S 350 Mercedes my back rear right door is not opening I can’t open it from the inside nor the outside do you think the WD-40 will work for my door if so where do you spray it