Facebook – Is it possible to see the deleted messages on Facebook Messenger

Here's how I get around it using Android Chrome:

1. Go to m.facebook.com
2. Click on the Chrome menu dropdown on the far right of the address bar
3. Toggle the "Request desktop site" option
4. Now click on the FB messages tab

You may not have the desktop site option depending on your phone. I'm not aware of any other way to do this.

No, when you delete a post, it get deleted from your Timeline and no one can see this including you.

However, it might not always be instant as sometimes there is a delay in synchronizing between servers.

But this page claimed that,

You’d hope that by clicking delete, your content is permanently removed. Apparently, that’s not quite the case. New evidence suggests that Facebook might not really be deleting the posts you think you’re getting rid of. In fact, sometimes these deleted Facebook posts are reappearing.