Well TurboT,
you should like inside the vi's used for writing the file!
If this isn't possible it will be a hard task. You can try to guess the structure of your file. The more you know about the content of the file the easier it may be to find the file structure...
Best regards,
GerdW

using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019