Sounds a lot like the thread brookn posted as a link; can a phal survive without leaves. I have had a phal start to rot and drop all its leaves, even before the leaves had fully yellowed. Its terribly discouraging
, and I'm not sure it can be revived. If it can, it will take a lot of tender loving care. If the phal is indeed completely leafless now, it is possible to still use photosynthesis on any other green part (like roots), just not as efficiently or effectively. So it does have hope (I think), but the light conditions will need to be really good for it get energy, along with other culture needs.
As for mealy bugs, I have no expertise on this critter
If its mealy bugs, others more informed will be able to help you with that. Good luck!