1. If the video cannot be played, the first thing to do is to download a video player again. You can download one with your mobile assistant.

2. After downloading and installing successfully, try to play the video with a new player.

3. It's better if you can play. If you can't play it, you must find another way to open the memory card of your mobile phone and find the video viewing properties.

4. When you find this video, you should first export the HD video of 1080 to your computer.

5. Open the format conversion software and convert this 1080 file into a 3gp file.

6. After the conversion, copy the converted file to the original memory card.

7. Delete the original video, click the new video again, and try to play it with the built-in player or the newly downloaded player.