Answer: Weeping mulberries are grafted trees. The weeping portion is attached to a separate rootstock, the graft where they are joined together is near the top of the tree (where the branches begin on the trunk.) Based on your description of the leafless tree, unfortunately, I think the grafted-on desired top portion has died. The new growth you are seeing at the base from the trunk or from the ground would be coming from the rootstock. If this is true, it needs to be replaced.
I should mention that the soil should be kept evenly moist like a wrung out sponge, not sopping wet/saturated and not dried out. This is optimal for healthy root growth. If the soil is too wet it can lead to the roots rotting.
I'm sorry about your tree.
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