If what is broken off is a leaf - you can trim the leaf stem with a sharp blade - and either root it in a soil in a baggie - or in a glass of water -wrap the top of the glass with a foil, punch a small hole - and insert the stem - so it is in a water - and a leaf blade is not. Depending on how fresh the leaf is - it should send roots in a couple of weeks.

If your plant has a main stem broken - you can root it as well - but ask for more instructions.

I.