Sorry for the caps, but I tried everything to extract the vocals from this song, but nothing seems to be working.
Using guides from Youtube, I tried to take this Beatles song ‘I Me Mine’: http://www.youtube.com/watch?v=NvDHwVM-PJI and extract the vocals so I can make a mashup for a project.
PLEASE HELP! It’s so frustrating 
It seemed to work perfectly for me. I’m in Audacity 1.3.13 and I captured the music you indicated. I applied Vocal Isolation with 20 2000 settings and everything else default. The voice obediently vanished.
Just so I understand, I extracted the vocal and threw it away. Did you want to save the vocal? You can’t do that in Audacity.
Koz
Wait what?
So if I extract the vocals, I can’t mix it up w/ a different instrumental?
If the vocals are panned dead centre and other instruments are not, then it is easy to remove the (centre panned) vocal (as described here: http://manual.audacityteam.org/man/Vocal_Remover ) This works very well for the beginning section of that track
If you want to keep the vocal (isolate the vocal), then that is much harder to do because there is no simple mathematical trick to “cancel out” the music leaving only the voice.
There are some plug-in effects that use complex analysis methods to attempt to achieve vocal isolation, though usually they are not able to achieve very much isolation without also creating a lot of damage to the audio. In certain cases with just the right sort of audio material they can sometimes produce impressive results, so you may get lucky. One such plug-in is Elevayta Extra Boy - it is a commercial (non-free) plug-in, but a free demo version is available if you want to try it: http://www.elevayta.net/product13.htm
Here’s a quick attempt at vocal isolation using the demo version of Elevayta Extra Boy.
Better results may be possible if you spend more time tweaking the settings.