Help with new computer board and now cannot play video

Hi, Thanks for your help. I have Catalina 10.15.7

My computer stopped working and I had it fixed by apple care and it has a new board in it. Seems to be working great but the videos are not playing. Even the videos that I just took. The photos look ok but the videos say "Photos cannot play this video because the resource is unavailable. I see someone replied 3 years ago with same problem and it talks of "if you copied a video from another device or disk but only the container, without the referenced video resource in that case you need to connect the old drive or disk so photos can access the missing video component. or 2 is the file system format of the volume where the video is stored maybe incompatible with photos , example if the volume has a case sensitive format, photos may not be a lea to find the resources inside 3. old videos maybe using codec, the version of photos can no longer handle ......I do not understand what all that means. I am super upset as I treasure all my videos. is there another program that I should use? any help is appreciated. thanks so much for your time and smartness!