How do I fix the video file

I am my brother's MP4 video to my MP4 cut, cut, but finished only take a few seconds, can not, later found to have a paper and he was the (.THM extension) However, the card when they put together, can not be released, how do I fix it ??????????? Who can help me!

to download a video editor! The function repair there! Can not be repaired, but probably not transfer files you just finished moving out of the disk, causing damage to the paper ~ ~