All the leaves have fallen off of my Ficus tree. Will they grow back? What would cause the leaves to turn yellow and fall off?
Very likely they'll grow back. Ficus are well known for throwing hissy fits and dropping all their leaves at the slightest change in environment, or if you look at them funny. They're very finicky.
Find a tiny branch you can cut off, see if it's dead (brown) inside or has a thin green layer. If it's still green be patient, it'll come back. Keep giving it water and light.
If the branch is dead, keep working back to larger branches till you find one that's alive. How far you must go back to find life will give you a good sense of how well the tree is doing.