Hi

I am using IE 11 on windows 7, I used to download some video files from YouTube which was working fine, now after downloaded video file is opening but audio is not working on any player (wmp, vlc, real player). If I download video files from YouTube using Firefox, chorme browser is working fine. Please help me to solve this problem

I wasn't aware YouTube has a download option. In fact I just went and looked and didn't see one. You usually would use a third party program to do that. Namely to capture and save the video stream in any number of formats.

That is weird.

I use youtubedownloaderhd. Google it.
Or the website: KeepVid: Download and save any video from Youtube, Dailymotion, Metacafe, iFilm and more!

Hope this helps
Grant