You will need
https://www.fonelab.com/ios-data-recovery/FoneLab%20iPhone%20Data%20Recovery to help you get the deleted text message back.
First of all, you should stop using your device, otherwise the lost data will be overwritten by new data.
Then, you should go to
https://www.fonelab.com/ios-data-recovery/ to download the windows or Mac version program on your computer.
Below is the detail demonstration with clear instruction.
1. For iPhone 4 and iPhone 3GS users, you need to enter the DFU mode before scanning the device. Keep your device connected to computer and follow the instruction on the screen step by step. For users of other iPhone types, including iPhone 6s/6s Plus/6/6 Plus/5s/5c/5/4S, you can skip this step.
2. Click Start Scan. Seconds later, all the data in your iPhone will be scanned and listed out.
3. If you just want to recover deleted text messages on iPhone, firstly you should uncheck your iPhone on the left. Then click Messages and turn on "Only display the deleted item(s)". Check what you need one by one and click the Recover button, soon the deleted messages will be exported to the Output Folder.
That's all. So easy, right?