If the file doesn't have a proper dot before "m4a," try renaming it to RecordTMP (32).m4a to see if your computer recognizes it.
How to Recover Corrupted Audio Files
Apps like GarageBand or Audacity may create .tmp or RecordTMP files while you are recording to ensure data isn't lost if the program closes unexpectedly. How to Access or Fix the File RecordTMP (32) m4a