RE: Left rear door won't open
if it helps at all, the lower brackets on mine are rusted to crap, but I wire brushed them when I got the truck, and spray them with lube. the brackets on the door frame.
try spraying some PB Blaster in there.
but seriously, also check to see if the control cable snapped, or came off one of its connection points.
those door panels are easy to pull off.
just pull the screw in the non moving handle area. remove the screw that holds the moving handle in.
and yank on it around the window.
just be carefull not to break it near the front of the door where it is just a narrow strip.
(check for extra screws first)