There is only one file type that uses the .TX_ extension:
Compressed Text File
A TX_ file is a compressed .TXT file typically created by Makecab, a Windows utility used for compressing files and generating .CAB files. It is often used for saving a TXT file to a CD so that it uses less disc space.
To decompress a TX_ file in Windows with Microsoft Expand installed, type the following command:
expand myfile.tx_ myfile.txt
NOTE: The underscore syntax is also used for many other compressed file types, including .EX_, .DL_, and .SY_.
|Microsoft Expand — Discontinued||Included|
Updated: September 6, 2019