How do I remove the red X on the left side of Filename for some of my song names

Support
1

red X on the left side of Filename for some of my song names.

2

By using one of the fixing tools:

You can see the reason for the X error icon in the "Tag" column of that file in Mp3tag's File List.

3

I would not go about with too high hopes: in some cases the tools can repair the files but by far not in all.
The red X means that something is wrong with the files - perhaps even so wrong that they are damaged beyond repair.