Certified GKH Gardening Expert
I am puzzled about your question. Generally, these plants are quite hardy in your region, as they're warm-season grasses and Florida rarely suffers from too many harsh winters. Are you certain they are dead. Perhaps your fountain grass is still dormant. They typically emerge in late spring to early summer.
Here is an article that you may find helpful: https://www.gardeningknowhow.com/ornamental/foliage/fountain-grass/tips-for-care-of-fountain-grass.htm