Q.I Just Purchased A Pink Flossy Silk Seedling. It Is About 12″ Tall. The Wind Blow It Over And Broke The Top Off.
Can I root the broken limb and do I need to do anything to the top that is still in the soil?

Certified GKH Gardening Expert
I would try to root the cutting. Hopefully, since your tree is small, topping it will encourage branching. You don't need to do anything to the remaining stalk.
Here is information on rooting cuttings and taking care of a floss silk tree.
https://www.gardeningknowhow.com/ornamental/trees/silk-floss/floss-silk-tree-planting.htm
https://www.gardeningknowhow.com/ornamental/trees/tgen/planting-trees-from-twigs.htm