i accidently deleted my text messages. How can I retrive them

If you have activated iCloud Messages (Settings > your name > iCloud > Messages = On) you cannot recover them.

If you have not done that and the messages were in your last backup you can restore your iPhone from that backup. You will lose any data added since the time/date of that backup. Restore your iPhone, iPad, or iPod touch from a backup - Apple Support

If they aren't in a backup they are gone.

If you have another Apple device, open Messages, open the message and simply reply to sync it back. 😉