Separating Instrumentals and Audio into 2 separate channels

I’ve been trying to remix a certain song and i’m having a hard time isolating the vocals from the instruments. I have tried everything on the isolate vocals tutorial page and i can’t seem to make it. It ends up sounding like the full song if it was played through a beat up jukebox. Any suggestions?

You mean this page? Tutorial - Vocal Removal and Isolation - Audacity Manual

Did you read the top paragraph where it says:

This page describes techniques which, on > some > stereo tracks, > may > allow you to remove or isolate vocals (or other parts of a recording) from the rest. There is no universal, reliable way of doing this without having the original multi-track recordings.

The implication is that for some (many) recordings, it is virtually impossible to separate vocals from the instruments. If you’ve tried all of the suggestions with no success, then it is very likely that the recording is one of the many recordings that vocal removal / isolation simply does not work for.