Can a data recovery software retrieve all chat history deleted previously on facebook?

[Dont you]

Face book typically stores it's files on it's own servers and doesn't let people log in to run recovery programs without a warrant signed by a judge. He can't do anything from his computer unless he had something that stored messages on it. Your friend if she has files on her computer can download the program ccleaner and set it to the most secure mode and clear everything possibly stored just in case he were to somehow be able to get access to her computer. That means 35 passes, guzman style deletion, wipe free space and alternate data clusters and check pretty much every box to be checked. Even the NSA would have a hard time recovering information after that.

However odds are the boyfriend can't do anything unless he recorded messages on his face book. Unless they live together he won't even have access to her computer. All she's got to do is delete the messages she doesn't want then make sure she doesn't have anything that saves sent messages on facebook. If she does she'll have to clear that out too.