@mrb767
The most likely reason for not receiving a password reset email is that you are somehow inadvertently using an email address that is different from the one you were previously using to log into the Google Nest app. My guess is that if the email address you're trying is not in Google Nest's customer database, it would be bad security practice for them to do anything but simply not respond.
It's probably not likely, but you could contact Support to see if the password reset function is currently broken:
1. Go to https://support.google.com/googlenest/gethelp.
2. Select a category/product family, and type in a brief description of the issue, then click "Next".
3. Click "Other", then click "Next step".
4. Under "Resources", just click "Next step". (Clicking one of the listed links will bring up a Help page.)
5. Under "Contact options", choose to get a phone call or chat with the team, depending on availability in your country.
