Many audio players in windows are greedy to become the default player to open your audio files. So at some point the real player has stolen this position. To change it to program of choice, right-click an mp3 & choose open with ... choose your program, then tick the box that says open all files with this program. You should repeat this process with all audio types of files including mp4 files, etc. More about this here:
Setting default audio program. After changing the default audio program back to your choice, the icons of audio files will also change back.