In my phone settings Norton was clicked to delete all my txt messages after a year. Obviously I didn’t know this was selected and have lost everything.
Is there a way I can get them all back ?
The setting you mention has nothing to do with Norton. That is just an iOS setting for Messages. Settings > Messages > Keep Messages. From there you choose between 30 days, 1 year or forever.
This Apple guide might help you recover deleted messages. https://support.apple.com/en-ca/guide/iphone/iph16ecebf48/ios