You posted your question to the Garmin Connect Web forum. Was it by mistake, or did you want to ask about Garmin Connect Mobile Android or iOS instead? If so which one?
Since there is (AFAIK ) no "My Day" in the Web app, I assume you mistook, and wanted to ask about the mobile app. In that case try clearing the cache of the Connect app, stopping and restarting it, or even rebooting the phone, and then scroll again at the bottom of the My Day screen, and tap the Edit My Day link. If the option is still not there, please post a screenshot.
Also make sure the watch was not removed from the account - check whether its icon still appears at the top
