So I made this Youtube intro and the audio does not work when i render it. I have tried a few things but i won’t work.
Here is a download link for anyone who would like to help. 
Download: http://www.mediafire.com/download/ooc0d40dlh7wvmu/introprojectbackup2.blend
Your file does not include the .mp3 file so we’ll have to assume there was some audio playing from the file within the render frame range.
What format do you want to create. Substituting another .mp3 file I get a unsupported codec combination error.
If you want Ogg Theora then set encoding preset to Theora or Format to ogg and the audio to FLAC
Tested this and it outputs video with audio (played back in vlc)
Did you set the Audio encoding?
Example below:
Fig 1 - Not set
Fig 2 - Set - Spot the difference…
I rendered a whole video (took 4 days to render) and forgot to set this - much swearing later I realised my mistake!
Cheers, Clock