Quick note ; try unmounting and then mounting the sd card from settings > storage . do this first if not ;
Uhm. Yeah okay. Make sure that the title of the song is the same as the .mp3 name with its accents.
Do this, delete the song from the phone and try renaming the "title"(on windows, you name title by going property > details tab [I guess] and then in tittle you name it as supposed.) with its accent. Then transfer it back to your phone and restart the phone.