Hello Glenda1111,
Thanks for reaching out to the Apple Support Communities! I understand from your post that you have been unable to use the "thumbs up" within a conversation.
You mentioned this is happening in Messenger, which is a part of Facebook. To be sure that we're on the same page, is this happening within Facebook Messenger or the Messages app?
If it's happening within the Messages app, check to see if you can use the thumbs up Tapback message effect with another conversation. Check out the steps provided under, "Add a Tapback to a message," in this article: Use Messages with your Mac.
If it is not working with any of the conversations in Messages, follow these steps:
1 - Quit Messages. If it will not quit, follow these steps to force it to quit: How to force an app to quit on your Mac.
2 - Hold down the shift key on the left side of the keyboard and launch Messages. When the icon begins to bounce, release the shift key. See if the thumbs up Tapback will now work.
If it still will not work, continue with these steps:
3 - Restart in safe mode and test again: Use safe mode to isolate issues with your Mac.
4 - If still not working in safe mode, you’ll need to create a new user and test it out again. This article will show you how: How to test an issue in another user account on your Mac.
All the best!