iust

hi every body last week I wanted to backup a video from my dvr on usb disk but dvr restarted suddenly so my file has disappeared from hdd I attached hdd on my pc. Hdd is full of video mp4 format with jdx files. these open and play but have not any video. just show dvr brand all of time of video. I try more than 20 famous players dvr brand is xampix (Chinese brand) how can I play the files by slave/master dvr hdd??