My video won’t show in the box, meaning i can’t edit it.

Okay so recently i shot a video to upload to youtube, but when i went to edit the video like i normally do, on windows movie maker, it loaded the video but you can't see it in the box; the box is just plain black. Also i have tried using photos and they work but after trying several other videos i found it was just videos that don't show. Also the audio from the video doesn't play but if i add music it does...

Any suggestions?

Thanks