Movie Maker Project – No Sound

Have experienced problems with my last few videos.

Upload video footage (with sound) to Movie Maker and when I commence editing there is no sound.

Previously I have re-started my computer and it came good.

Last night I made a very short edit of some footage and uploaded it to Youtube and it had sound but there was none during the editing process.

Same problem today, re-start didn't fix it.

I am at a loss.

Any suggestions?

Thanks