Whether or not the content of text messages is still available depends on a number of things. You will always be able to get a copy of the log showing messages were sent and received (may have to be done by an attorney via subpoena). BUT, all cell providers have their own policies for how long they hang on to the content of the messages themselves. For example, Verizon says they delete all content within 30 days I believe.
I know that there are data recovery programs that may be able to recover some of the deleted data. My BH used some of them for my phone. It is worth looking into that.
Digital information in a Gmail account (or yahoo etc) might not be easily accessible to you personally. It might require legal assistance to obtain that information. The truth is, nothing erased is gone forever. That information may still be stored by the service provider. You should reach out to them and ask them what their policy is. It will also be located in their privacy and end-user agreement.
[This message edited by Wayflost at 12:38 PM, July 9th (Wednesday)]