Hi, and welcome back to JustAnswer. Unfortunately, once they are deleted from the phone, no one can retrieve these, but depending on the importance level of getting to these messages, I believe Verizon themselves keep an archive of all text messages sent and received from your phone. Have you checked to make sure they're truly deleted, and not just sitting in a trash folder or something? I'm not sure what type of phone you have, so I don't know if this is an available option for you.
If all else fails, though, contact Verizon. They should be able to provide this information to you.
I hope this helps.
I apologize, I wasn't aware of the severity of your request (the optional comments didn't show on my end at first). Yes, Verizon has been required by subpoena to turn over text messages in the past by several U.S. Justice Department judges, in the cases where the prosecutor can prove that the records are 'relevant and material' to an investigation. How far back they keep this information seems to be a well-kept secret, however. But I have seen cases where information about text message received over 6 months ago has been provided, so I would say with about 95% certainty that your messages are archived and available.
Here's an article referencing one of the cases I mentioned above:
I really do hope this helps your case.