I'm new to Movie Maker and Windows 8 so any help would be greatly appreciated.

I have a project to do for my course (deadline creeping closer!), which involves editing film of a lesson down to an hour.  While I was filming, I checked the playback regularly and there was sound.

When I tried to edit the film there was no sound.  Where has it gone?!  How can I get it back?

I know this has been asked before but some of the answers didn't seem to apply to me and some I just didn't understand!

Please help