Windows 10 do not play videos or sound

Hi,

I upgraded from windows 7 to windows 10 and since then I cannot play online movies (mp4) or in real player I can play the movie but without sound. I am always being told to download Flash player which is already pre-installed in windows 10. Everytime I try to downloaded Adobe shows me how to got advance settings to chech that the indicator is enable, which I know it is as alresdy I  hav done it.

Any ideas or leads on how to reslove that issue.

Thank you

Emmanuel