I am trying to find some old SMS messages from about a year ago and I see that all my MMS messages with this person are still there but the SMS messages are gone...until about February (9 months ago) when they all start appearing again as normal. From what I can tell it is only doing it for this one contact (my girlfriend...so there are lots of messages there). The setting re deleting old text messages is NOT enabled (and never has been) so I am not sure where they have gone or if they can be retrieved. Might the phone have archived them for this particular contact? I am using the standard messaging app on Samsung Galaxy S8. Software is up to date. Any help greatly appreciated.