Check your Ringtones
When I got our Nexus7 tablet over a year ago, I was happy to find that it would accept WAV files as notifications and ring tones since I had a number of custom WAV files that I wanted to use for different needs.
In addition I used SmartVoiceRecorder to generate a custom voice ringtone for my wife (who has difficulty hearing and finds it easier to hear alerts recorded with my voice) and it worked fine using the WAV files that it generates.
Over the last couple of days, her phone stopped ringing. Her settings showed that the ringtone was set to "none"
Using SmartVoiceRecorder to reset my recordings to "ringtone" didn't work either. Copying the WAV files to the ringtone directory and selecting them using ES File Explorer also didn't work.
None of the above actions triggered any warning or complaint, but the current ringtone was reset to "none" after each attempt without warning or notification.
I checked the SMS message tone and found that it had also reset to none.
Not sure if there is an android app to convert WAV to an android acceptable ringtone, but [Only registered and activated users can see links. Click Here To Register...] is a nice little PC converter that creates mobile compatible audio files... I tried AMR and OGG outputs, and both worked as Nexus ringtones.
Hope that this information is of value.
Re: Check your Ringtones
Thanks for sharing. Glad you got something to work.
From a Sprint Moto X using AC forums app