Hidden messages on Facebook Messenger can be found in message requests and hidden chats. If you want to access them, do the following: 1. Open Facebook. 2. Click on the Messenger icon in the upper-right corner. 3. Go to See all in Messenger. 4. Click on the three dots on the left side menu. 5. Go to Message Requests or Hidden Chats. To search for contacts in your message requests, click on the search bar on the list of conversations on the left side of your screen. To find hidden messages on Facebook Messenger on your phone, do the following: 1. Open the app. 2. Tap on your profile picture in the upper-left corner. 3. Go to Message Requests. 4. Select the You may know category or Spam.