Unfortunately, the only way to obtain the corrupted main menu theme again is to return the game to its default state and delete your data ^^;
If you don't mind doing that, you can visit the "manage data" screen (found in the main menu) and choose the "delete stored data/start fresh" option. While this option won't delete your save files, they're unlikely to work anyway.
Please keep in mind that returning the game to its default state will also reset all your achievements and require you to start over ;n;