Q&A: How could I soften fondant when is already rock hard?

You can microwave it for a few seconds to soften enough to knead, then add a bit of shortening. Knead thoroughly. You van also add a bit of glyerin.

Microwave for 5 to 6 seconds n then knead it for few minutes wearing gloves.
Add little shortening while kneading.

Si ,microondas, pero tienes que trabajarlo muy rapido, porque enseguida endurece y puerde propiedades, para forrar, yo te recomendarua que despues de calentarlo lo mezcles a partes iguales con fondant mas blando y lo trabajaras mejir, o con chocolate plastico.

Thank you “Secretos verde violeta”, “Sandra” and “Rakhee” for answering my question, I really appreciate it.