Depending on what you remember about the sender of the message or the characteristics of the message, a different way of looking for it might make the most sense.
Find a chat based on a person’s name
Type the person’s name in the command box at the top of the app. You’ll see their name and any group chats they’re a part of with you listed. Select their name to go to your one-on-one chat with them, or a group chat to resume that one.
Find a message that has a keyword that you remember
Start typing a keyword into the command box at the top of the app and press Enter. You’ll see a list of results that include the keyword.
Filter to show certain types of messages
From the Activity feed, select Filter 
to show certain types of messages such as unread messages, @mentions, replies, and likes. For a more specific search, go to the Feed menu and select My Activity.
Find your saved messages
To save a message, select Save message 
just to the right of the text.
To see a list of your saved messages, select your profile picture at the top of the app, then choose Saved. Or just type /saved in the command box at the top of the app.
