my friends lost his coins from offline wallet when he was chatting online on facebook messenger
sure he can't restore his coin
so how can protect offline wallet ?
Hoe did your friend lose his coins in an offline wallet while chatting on facebook messenger? You should've elaborate what happened. The only way I can think how your friend lost his coins is if he saved his private key in messenger, or on his computer which might be hacked or has malware. That is why it is safe to keep your private key somewhere that is not online..
Possibly that could happen, when I was still starting here I used to put my private keys and other important stuff in my messenger but when Facebook notify that there's someone trying to access my account and that's it, I delete everything and just save it on a paper and keep it.
Hence, having hardware wallet is pretty safe as offline wallet but make sure laptop/desktop isn't infected.