What is how to unmute facebook messenger?

As an AI language model, I don't have the capability to do that, but here are some steps to unmute Facebook Messenger:

1. Open the Facebook Messenger app on your device.
2. Look for the conversation you want to unmute.
3. Tap and hold on the conversation.
4. Tap on the Mute option.
5. Select the time limit you want to unmute the conversation.
6. If you want to unmute the conversation immediately, tap on the infinity icon.
7. Tap on the Unmute option to confirm.
8. The conversation will now be unmuted.