Broken sunflower

I am growing sunflowers and I had a stem folder holding the stalk however it must have been removed because i found it broken today when I got home and theres no way it would have broken if it was in the holder. How can I mend the stalk and salvage my sunflower? It just bloomed one flower and there are 3 moire buds waiting to bloom. The stalk is not completely seperated from itself but partly is. Is there a way to mend it?