Hi, thank you for contacting JustAnswer.com. My name is Russell. I aim to answer your question satisfactorily.
Do you mean that you broke the case that the wristband attaches to?
If so, the case must be replaced, yes.
That should be done by a professional-level (or, fairly high-level) jeweler or watch shop.
The pro-level jeweler should be able to tell you, if I cannot. And I have to admit that, after a search, I cannot find replacement case parts for the Garmin 210.