Don't despair. Phals can come back from the dead (at least it would seem so). Keep them in a humid environment and they will probably eventually start to grow new roots. Once that happens, the roots can actually seem to grow fairly quickly. Then it may be a bit before you see other growth.
How are you feeding them? Definitely don't over feed. You are better off feeding at a super low dose.
Check out Ray's site for lots of good info
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Also, check out this thread for hope
Is it really still alive and not dead?!! Pics