Rear driver side door is locked

If I had to guess, I would speculate that your original rear drivers side door may have been damaged in an accident and was not properly repaired.

I've never had to do this with either of our Prii, but on other vehicles I have pried off the plastic trim on the inside of the door to get at latch attachments and power window motors. I can't imagine that the Prius doors have been designed any differently than any other car. It's probably best to use a pry tool to do the job, something that you could get at a Harbor Freight store, but if you are careful and go slowly you could probably use a large flat head screw driver as well to get the trim off. Before prying on the trim, though, make sure to take out any screws that you can see and loosen any pieces of chrome or plastic that they are holding down by gently wiggling on them. After removing the trim, I would expect that you might find damaged wires and latch pieces that will have to be repaired or replaced. The best source for replacement of those items is your local salvage yard. If the window will move in its present state, even though it does not do what you want it to, I would not expect that you would need to replace the window motor, which is probably the most expensive part, so that's good.

 

see if the bolts for the rear door are exposed when you open the front door.

 

Right, I guess if you can't get the door open at all, it may be hard to get the trim off, as it may be jammed against the weather stripping around the inside of the door frame. Hopefully, the door could be unbolted from the rest of the car by going at it from the front edge, and then after removing the door you should be able to pull the trim off.

 

It's a challenge, but I've seen success posts getting the trim off with the door closed, at least enough to get access to the latch.

In the worst case maybe the trim doesn't perfectly survive and you've got some of that to replace. There aren't a lot of other options.