"Send us a message" missing in messenger

Hey @Anusha Racheal from the support engineer team here👋 

There are a few reasons this could disappear! The most common are, your Messenger Settings here (make sure you check for users and visitors):

And another common reason would be volume control. When a customer uses the Messenger, all your assignment rules work in the background to predict which team inbox the conversation is more likely to get assigned to. If all teammates who belong to the predicted team inbox have reached their assignment limit or are set to away, the customer won’t see the “New conversation” button in the Messenger.