There are two ways to Recover Unsent Messages on Facebook Messenger: 1) First of all, try to Re-send the message from your phone or tablet. We can do this by opening the Messenger app and looking for the message that you want to send again. Tap on it and then enter the button of 'Send.' 2) Try Use to Different Facebook's web version of Facebook Messenger to re-send the message. Log into Facebook as normally and then go to this link: https://www.messenger.com/#!/chat/home?content= Source Link