In my case it was solved by removing .nomedia in the root of the SD card, copying the audio folder from the media folder to the root of the SD, and then moving it back to the media folder. Don't ask me why but it worked again.

In my OnePlus 2 running OxygenOS 2.2 (Android 5.1.1) the problem was solved by removing .nomedia in the root of the SD card, copying the audio folder from the media folder to the root of the SD, and then moving it back to the media folder. Don't ask me why but it worked again.

Had the same problem with a onepus two, oxygenos 2.2 (based on android 5.1.1) All of a sudden all my ringtones are default and I can not select any other ones on my sd card with es-filemanager (error: wrong file format, choose again). I could play wav files, not ogg or mp3. In my case it was solved by removing .nomedia in the root of the sd and copying the audio folder from the media folder to the root of the SD and then move it back again to the media folder. Don't ask me why but all worked again :-)

In my case it was solved by removing .nomedia in the root of the SD card, copying the audio folder from the media folder to the root of the SD, and then moving it back to the media folder. Don't ask me why but it worked again.