I find that when I go completely emotionally dead, a nice depressing
piece of horror story (Not a big budget 'horror' movie, they're boring
and fail to elicit anything but contempt from me) is generally enough
to get me back to my usual self. Pain is also good at accelerating a
break from the blankness, though I personally have always preferred
head injuries. (This has lessened as I have grown older, however:
nowadays smacking my head against something really, really hurts. When
I was a child, it was less injurious and more soothing)
I personally usually shut out the world for a day or two when I go
emotionally dead while I read depressing, moody things, but then, I've
never found the situation alarming, so I'm perhaps not the best
comparison point. Nobody has ever noticed it when I do it, for one.
Does she know what triggers it? Knowing the source could be useful for
working out the undo option.
Chocolate is also a good way of exiting this state quicker, in my
experience. Sugary candies usually make it into an out-and-out
physical depression for me, which I personally consider worse but I
imagine might be considered better by someone that finds a lack of
emotions alarming in and of itself. (Don't ask me why sugars make me
depressed but depressing stories get me over this faster in a non-
depressing manner, I honestly don't know)
If she absolutely must use pain to get out of it for whatever reason,
putting something cold on her knuckles (Or whatever) keeps the
swelling down and helps the injury heal more quickly.
Alternatively she could use this opportunity to achieve a better
understanding of herself and those around her, but if she finds it
sufficiently concerning to describe it as 'wrong' even when she has no
emotional state to speak of, I imagine that would be an undesirable
suggestion.