it seems like those files are compressed. You can read the article found here
which explains what this means.
To check if this is the case, all you have to do is right click the file, then properties. Then click the button labeled Advanced
near the bottom right hand corner.
If the box next the box next to Compress contents to save contents to save disk space
is ticked, then the files are compressed. you can uncheck the box to uncompress the file and the text should return to normal black colour