If your arm gets chopped off, you'll recover, and do fine (but without an arm). If a plant stem gets chopped off, it'll do fine, with one less stem. But plants keep sprouting stems!

When you can worry is when all the green on top gets removed.

A groundhog or vole took off a plant of mine near the soil line, and that did not recover, but yours still has branches and nodes where suckers will grow to replace the main stem. Don't pinch off the suckers, and everything will be fine.

Yes, I've once seen a seedling tomato resprout after it was sawed off by a cutworm, but generally, if you lose everything above the soil line, you're outta luck.

It is the groundhog. It is not deer. Absolutely sure, found a freshly made hole under Forsythia bush.

Groundhogs eat almost any young plants.