Facebook deleted comments are not always permanently deleted. They are only deleted from your view, but users can often retrieve old comments from the system because Facebook stores everything on its server. You can delete your account entirely and restore the account. Old messages are especially easy to retrieve, and a past, a bug in Facebook actually was restoring deleted messages automatically.
Facebook Archive Deleted Posts
Your deleted posts and associated comments are all archived out of sight within the Facebook ecosystem. For better or worse, you can retrieve everything in a few simple steps. Open a web browser and log in to your Facebook account. Click the arrow in the top right corner of the browser to open a drop-down menu. Click on the "Settings" option to open your general account settings. Click "Your Facebook Information" in the left panel of the screen. Select "Download Your Information" in the main screen to download a copy of all the information you have entered into Facebook. Click on posts to view all the posts you have ever entered on Facebook. Select comments to separately view every comment ever entered on Facebook.
Deleted Messages in Messenger
Retrieving deleted messages is also possible using the same archives system. It will separately open Messenger, and you can access the archives there. Messages that are manually deleted on both ends may not be retrieved. If another user has permanently blocked you, that also blocks and removes associated messages. The cord is cut, and retrieving Facebook deleted comments and posts associated with that individual is not an option. Otherwise, your historical archive of messages, comments and posts is all retrievable. The information management dashboard provides access to these archives along with archived photos, payments and almost every transaction you have processed through Facebook. You can manage location history, calls, and all personal information stored here. If you want to delete personal information, this is the dashboard to execute that task.
Commenting Best Practices
Knowing that Facebook keeps a permanent archive of every action you take, consider limiting your comments and posts. Avoid posting anything based on emotion that you may regret at a later time. Everything said remains in the system and can become incriminating or regrettable in the future. Ideally, Facebook is used lightly to communicate with friends and family or to follow and engage with businesses. Steer clear of the politics and manage sensitive conversations in person or over the phone to avoid the permanent record.