MacBook video HELP!!

My MacBook had always uploaded videos from my Nikon camera with no issue, it uses the software that came with the camera to take videos and pictures off and put them on the hard drive. Today, it appears to have loaded, then when I search for the video like I always have, it's nowhere to be found. Every attempt to load the same video afterwards has the same outcome, appears to work then nothing...help? I'm using a MacBook bought in 2006