Is there software to find audio that was lost , when trying to record from an hd camcorder?

-Hello i recorded this event the other day i took maybe 18 videos (so while i did get the gist of the event )but 3 videos i took the external mic was not in all the way and i could not hear any audio.



but this camera also has a internal mic that it records to at the same time i had the mixer set to record 3/4 of the external mic and 1/4 the internal.



but when i play the video i just hear garble and noise i was wondering if there was some software i could use to just erase the bad audio and use the internal audio is there?



I do have pinnacle studio i know you can import video and turn up or turn down the audio but not sure if they have a feauture i could remove the bad audio and use the external audio let me know.



thanks