Try the following troubleshooting steps -
- Codec Issues: The video file might be using a codec that Windows Media Player doesn’t support. You can try installing the necessary codecs or using a different media player that supports a wider range of codecs.
- File Corruption: The file might be corrupted, even if it shows the correct size. This can happen during the transfer process. Try downloading the file again.
- File Extension: Ensure that the file extension matches the actual format of the video.
- Update Drivers: Outdated graphics drivers can cause playback issues. Make sure your graphics drivers are up to date.
Check these links form Microsoft for troubleshooting -