AVI files no audio/VLC not working

When downloading avi files quicktime is selected and although there is video there is no audio. I've downloaded every version of VLC but the computer doesn't seem to recognise it - even when hitting on the vlc cone icon the top menu bar doesn't alter i.e go from finder to VLC. I've never had a problem with vlc before however my mac recently crashed and am currently operating out of the root system administrator so don't know if I'm missing some plug in that I might have had before. Please help and be as clear as possible as I'm not that computer savvy. However, I'm great with women, and will gladly instruct on this front in exchange should you need some macdaddy expertise.

 

Thanks just tried and still not working!