My text messages being auto deleted.

If you do not have a backup prior those messages being deleted, then they are gone.

Did you check to make sure that a back up was not completed automatically to your icloud?

Settings>[yourmane]>icloud>icloud back up from there you may see a recent one, if it backed up

It is understandable why some of us don't have back ups and agree that your question was not why you do not have one. If you do not have one now and the messages are gone - your now realizing you should have.

We live and we learn, sometimes the hard way. There is no need to laugh at someone's face for this.

With the way things are today - viruses and scams, technical difficulties and breakdowns, it is a great recommendation to make sure you've got yourself covered. Just like having insurance on a car or a spare tire in your trunk - without those we can find ourselves lost. Although some of us wish that we put that spare tire in our trunk when another tire is blown we overlook things as life passes so fast and wished when needed that tire was there. - if that makes sense.

We are only human and nobody is perfect. As mentioned, we live we learn. I don't think your any different.

abbyfromPA44 wrote:

If the message occurred before a backup could be made and then was Auto-deleted...

You stated you "hadn't done a back up". As there are no settings that auto-delete messages in less than 30 days, that would imply, given not further time frame on your part, that you were not doing daily back ups. If you are, as you should be, doing daily back ups, you wouldn't be losing much of anything.

If your phone is deleting things that are less than 30 days old, there is something seriously wrong. The first cause to check is how much memory you have. Settings>General>iPhone Storage. Having little to know space on the phone can cause all sorts of problems.

If you have enough space ( a couple of gigs at least), the next step would be to restore from a back up. Test. If that doesn't resolve the issue, restore as new (after having made a back up) and test.

There are, by the way, no viruses that will affect an iPhone unless it has been jailbroken.

If you do not have a back up that contains the messages, they are gone. Why on earth do you not have a back up?

How to back up your iPhone, iPad, and iPod touch - Apple Support

Viruses on iPhone not implied, just used as general context. No spare tire in your iPhone either