previous Library

my question is I have lost some music and I donot have the physical copy to redownload it. What I want to know is if I put the previous library on another computer. Will it show it up or have i lost the music for good. I donot want to mess with the one I have now but I am thinking of putting another computer and copy it over with cd. the Cd i had of the music is scratch and I had to get rid of it.