Compression (unless it's lossless compression, like .zip files) degrades the quality, it doesn't enhance it.
If the file plays on another player (and I doubt that it will), something very strange happened, because a phone comes with a player that can play the videos that the camera app it came with produced. What's more likely is that the file got corrupted, somehow. (There's nothing you can do about that but reshoot it - which is why you should always look at pics and videos at the time you take them (and if you're recording audio, listen to it as soon as you finish recording it).
Then make backups of all your important files, to at least 2 different locations - a PC and a cloud account, or two cloud accounts.