MediaPlayer failes to open the media file

Yesterday I made a simple system in UMG with 3 buttons , each of them plays a video on an Image when clicked.
It was working fine yesterday , I shut down the computer and slept , today the same system doesn’t work . it just shows blackscreen .
At first I thought there is a problem with the material that media player creates , but I noticed the sound is not playing as well , so I opened media player and I saw it says “The Media failed to open , check output log for detail” .
I opened the output log to see if something is up , and no , nothing related to mediaplayer is there .
I tested my movie clip , whichi is only 6mb .mp4 file , it is ok . created another mediaplayer , it wont play either , I created another source file and assigned the clip to it , still nothing !
This is annoying as hell when something works and suddenly stops working . I didn’t change unreal version or do anything to my project ! I cant understand how is this stable ?

Please attach your full log file, thanks!

I actually made it play Again , I converted the .mp4 to .Wmv . and now it plays again .
But mp4 files still fails to open .

Make sure you’re using a supported codec. H.264 is compatible with all platforms. MPEG-4 works on Windows and macOS. H.265 requires Windows 10. Some tools (including Adobe Premiere) like to encode with AVC1 by default (QuickTime), which is not a standard codec and only support on macOS/iOS out of the box.

I’ve encountered the same problem exactly as you say, I followed the tutouris by epic, but can’t funchtion well.

Did you enable the RenderDoc plugin? I had the same problem and found that disabling the plugin allowed me to open H.265 video.

What about Mac? Does anyone know how to fix this for Macs? There is no “DirectX” option under Mac - Platforms