I have a schefflera / umbrella plant that has suddenly dropped all of it's stems.

Nothing changed in it's care, same pot (7"diam), same location (south). But, I may have underwatered it, followed by overwatering, though my other schefflera is fine.

It has one stalk just over 2 feet tall. The stems started to droop, and some turned brown and fell off. The others were still vibrant green but appear to have drooped to the point that they snapped off the main stalk. The leaves are still attached. So now I have 4 stems with leaves in jars of water, and a bare stalk.

The top foot of the stock is distinctly darker and almost withered looking.

1) Can the main plant be salvaged? How? Do I cut off the top?

2) Can I root and grow new plants from the dropped stems and/or leaves?