A virus turn all my mp3 musics files to .exe extension and I don't want to use an Anti Virus for it . So I think I need some other ways to turn it back manually . If you can help then will appreciate it .

You can try any of these free file renamers: Best Free File Rename Utility (http://www.techsupportalert.com/best-free-rename-utility.htm)

1. Press the start orb.
2. Press Control Panel.
3. Press Appearance and Personalization.
4. Press Folder Options.
5. Press View.
6. Uncheck "Hide extensions for known file types."
7. Press apply.
Now just right click the file and go to .exe and change it to .mp3