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..
There might be two things being stolen when you use an offline wallet, your friend gives a private key to someone, or your computer has a virus. Giving someone a private key is the stupidest mistake made by a user. Private key is something that is very "private" and confidential. no one can know your private key including official third party. And the second is a virus or malware, I have experienced one of these things, I installed an application sent by my online friends, and it turns out that the application has malware that allows them to record all activities that you do in your computer, including recording passwords and private keys that you enter.
how to protect them is to install an antivirus and be careful of applications and suspicious links