HELP! No sound in iMovie, Mother's Day Project is Failing!

OK, so I decided to convert all our old home movies from our tape-based video camera to digital and make a home movie collection/DVD for my wife for Mother's day. The kids are psyched, etc. - all good.

Using a video converter, I coverted all our old tapes to digital mp4 files. Each 2 hour tape converted to roughly 2gb files each and they all play fine in itunes and quicktime. Yes, this was 16 hours worht of converting as they run real-time. I imported all 8 to a single event in imovie 09 and started dragging clips to a new project.

As of this afternoon, all the files would play in the imovie preview window with audio -- everythign was working perfectly. Tonight I go downstairs to try to finish the job and I can get no sound out of any previewing of the content in the event view or the project view. No audio at all. I double checked the files play with audio again outside of imovie. Nothing i try recovers the audio and I have found countless "no audio" posts on the internet regarding imovie, but I have found no solution

HELP! Mother's day is at risk here! 😟

Thanks!