It's like unbaking a cake. You cannot seperate the components once they've been combined. There is software that, thru various comb filters can remove a vocal track - karioke-ize the song. But there is no commercial or commonly availble software that can seperate a recorded song into its component tracks. All you can do is isolate frequencies. And instruments, or tracks if you will, produce a variety of frequencies. But it's the combining of the various frequencies that create the song. And once combined, cannot be uncombined.