Anybody handy with music production software?

[The Dirty Bubble]

A friend is getting married on Saturday and one of his mates is going to sing. The plan was to use the masters of one of his studio sessions as a backing track as it didnt have the vocal track. The problem is he has misplaced the master, all he has is an mp3 with the vocals and the music combined. Does anyone know how to remove the vocal from the track? I have tried using some software off the internet but it might as well be in a different languge.