300SD Issues

Hey guys, first I'd like to say I appreciate all of you guys out there willing to spend your free time helping guys like me out, who have no idea (or not enough of one) to fix their classic cars.

Now for my question(s), my drivers side doors have never opened from the outside. I'm not sure why, but it wasn't really a problem until yesterday when my cousin attempted to "unlock" them. Somehow he locked all of the doors and the trunk. I was able to unlock the passenger side doors, but still no luck on the trunk or the drivers side doors, even from the inside! LOL I'm currently crawling over the shifter to get in (and I'm 6'2, 280 pounds). You can only imagine what this does for my dating life. haha..

I do know that the drivers side door lock is broke off.

Thanks for any help you can provide. Also, if anyone knows of a great place to find little parts like switching and things like that for cheap preferrably used. Let me know.

Thanks,
Matt