My 1999 Toyota Sienna has a broken rear latch

I answered this for someone else -

If you still have the broken piece, you can try to use that to try to open the back. Otherwise, you have to open it from the inside.
I changed mine in 2007 so if memory serves me, I had to remove the back panel and pull on the cable to open the door.

Now to see and pull on the cable, and replace the latch, you have to take off the inside liner/panel to get to the latch to replace it. This took about 2 careful hours to replace.

The trick is to get the two side pieces off.
These two plastic pieces are next to the window on the left and right sides. Each piece is about 3 inches wide and 18 inches long. Using a strong grip, or a pry bar or large screwdriver, take off both pieces. There are three clip areas that holds each piece in.

If you are using a tool, be careful to protect the area by wrapping a towel on the screwdriver/tool.

After that the bottom liner piece pulls away and you can see the latch.
There are two screws/bolts that holds the latch.

The two pieces snaps back in pretty easily.

You probably broke the plastic piece shaped like a J.
You can try to glue the pieces back, but note that the piece broke due to age. I changed the whole assembly - good for another 7 yrs. I could not find just the plastic piece