Youtube Download ( C# )

I have a Youtube downloader in c#, I found it in some forum. The software download videos from youtube in several formats including HD. The problem is that this software worked perfect some months ago, but now it not work, maybe because youtube updates. Then I need somebody can fix it and also add conversion for videos to mp3. I will have priority to who have knowledge about Videos conversions or/and to somebody that developed youtube downloader before. If you have developed it in other language that don't need dependencies like .NET Framework etc, we can make deals. If you need source code of my project i can provide it by Freelancer's chat. Sorry my bad english. any questions by chat. Thanks.