Something seems to be eating my hosta roots. I have had some healthy hostas practically disappear.
I'm sorry that a garden visitor has found your hosta roots to be a tasty meal! Black vine weevils, also known as root weevils, are the usual suspect, and these articles may help you get rid of them:
It is also possible that a rabbit dug your hostas up, if there is not another more easily accessible food source in the vicinity. (I've personally had this happen. They also sometimes choose to bed down smack in the middle of the plant when it's still young, so if you see a clear depression in the middle, with the young leaves flattened in every direction away from the plant BEFORE it disappears, it's pretty safe to say it's a rabbit.)
This article may help you keep rabbits away from your Hostas (if you have them): https://www.gardeningknowhow.com/plant-problems/pests/animals/keep-rabbits-out-of-gardens.htm