My wife tries to open a rear door as I was unlocking it. The door stays locked, I tried again, and now neither rear door will unlock using the key, so turning the key doesn't unlock both front doors. Is there a way to reset the system so that the rear doors unlocked to? Or is it broken? Thanks as always!

I don't understand something. BOTH rear doors used to work? Do they unlock from the inside? Do the doors lock with the key or door lock button?

Here is a procedure to replace the latch:

http://volvospeed.com/volvo_repairs_how_tos/doors_latches/x70_latch_repair.html

This is an 'old' problem. Until you remove the door panel, it is hard to diagnose. It could be just a bent rod or a rod that fell out of position.

I wouldn't try 'fixing' the Red Evil Plastic Lever (REPL), too much work.
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Keeping it running is better than buying new

YOU broke it! Not your wife's fault that you were too slow to unlock the car.

I would go to a junk yard and hope that a replacement(s) isn't also broken. Yes, the red plastic can be 'repaired', but it is a real pain to do.
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Keeping it running is better than buying new

Thanks Klaus! What am I looking for to replace?