This guide will show you how to unarchive a conversation on Facebook Messenger by sending a new message to someone you had archived before.
Steps

Open the Facebook Messenger app. The Facebook Messenger app icon is a blue chat bubble with a white lightning bolt in the center.

Tap on the search bar at the top of the screen.

Enter the name of the person whose conversation you had archived earlier.

Tap on the name of the person you want to unarchive. This will open the chat, and the archived conversation will be displayed.

Type a new message.

Press the blue send button. The send button is located on the right side of the message bar, shaped like a blue paper airplane or the word 'Send' in blue. This will send a new message to the recipient and move your conversation from the archive to the inbox.
