Do you see any audio file on the audio layer ?
if yes, does it have sound waves ?
please let us know
Do you have full version or Trial version of PPRO ?
Provide exact model of camera, and what are your recording settings?
if you can hear the audio with media player or with any other player in your computer then check settings
EDIT--PREFERENCES--AUDIO HARDWARE AND CLICK ON ASIO SETTINGS.
another dialog box will appear and in that under
INPUT AND OUTPUT TAB
MAKE SURE ALL THE OPTIONS/BOXES SHOULD BE CHECKED .
DO NOT FORGET TO UPDATE TO 5.0.3