mrkhaled Can be a bunch of things. This sounds like a codec issue.
Could you check if the following codecs are installed on your Windows system?
HEVC - h265 video files up to 8k with app
Microsoft store - It is $1/1€ however
or get it free here. (see attacked image below which one you need.)
AVC - h264 video files up to 4k in web-browser and app
K-Lite codec pack -OR- LAV Filter pack - Both are Free
NOTE! If you already bought the HEVC codec then this is still available in your Microsoft account on their app store!

If you already installed these previously, it is possible something changed, deleted or uninstalled one or more parts. The K-Lite codec pack comes with a tool that can reset everything back to their defaults. Press the windows key and type codec tweak tool.
