Q.Yucca
My yucca was very badly hit by severe frost and looks to be in a very bad state. Is there anything I can do to give it a kick start? It’s about 10 years old.

Certified GKH Gardening Expert
If the stems are still alive, they will regrow their leaves and there is also a chance the roots are alive and they will regrow from the roots. I would give them a month, and if you do not see growth by then, they are most likely dead. These articles will help you as well:
https://www.gardeningknowhow.com/plant-problems/environmental/how-to-tell-if-a-plant-is-dead-and-how-to-recover-an-almost-dead-plant.htm
https://www.gardeningknowhow.com/plant-problems/environmental/tips-for-saving-cold-damaged-plants.htm
https://www.gardeningknowhow.com/ornamental/foliage/yucca/yucca-cold-weather.htm