How to restore hidden messages on mobile phones?

Is it one person or everyone? Can't it be restored in the SMS settings? Or is it encrypted and you forgot your password? For example, I once encrypted and hid a friend's message myself. I can receive his message, but I can't see it. I forgot the password. Finally, I had to save his number again. There used to be a famous surname. Now I save it directly under my name, and the message he sent before can be seen again. If not, call 10086 or the manual station of your mobile phone brand company.