Thanks for reaching out. Let's go ahead and see what we can do here. To confirm, do you have the wired or battery type of Nest doorbell? In case you have the Nest Hello doorbell, you'll see its preview from the home page of your Nest app and you should see the option to turn it on. If not, tap the tile of your Nest Hello doorbell> settings> turn it on.
Looking forward to your response.
You're welcome! As we got our resolution here, I'm going to mark this thread as resolved. I'll be locking this thread if we won't hear back from you again in 24 hours. Should that happen, feel free to create a new one if you have more questions or have other concerns in the future.