Use a different media player which supports the video codec.
Maybe the video is corrupted.
Whilst screenshots often help, in this case I don't feel they do.
Which video player are you using and what version is it?
What video are you trying to play.
Which version of OxygenOS are you using?
Etc, etc - details please. Help us to help you.
if you don't know the file format just try different media player like MX player, VLC media player
or may be your file is corrupted
Gamme OnePlus 7 : Avis et faites passer le mot.
by Vito B., 2019-06-17