Run this python program in your computer and follow the steps.

Running program:
1. go to the directory the programs are located
2. open command shell
3. type: python VideoSubUnite.py
4. follow the on screen instructions

This program is run in a directory where you have videos and subtitle files.

Each video may have a sub file associated with it but it may not have the same name as the sub file which is why on opening your video player it is not detected and you have to add the subtitle manually

The subtitle file corresponding to the video file is detected and the name is changed