data on my hard drive that has been *deleted' but not over written

Is there anyway that I can see this and recover it? I have a disaster with iTunes and Timemachine and have lost about 600 cds as my hard drive failed and unbeknown to me the Time machine wasn't backing it up. The volume appeared but was empty. However I know that previous to a new global back up I did on the TM it was all there; so I think it still may be on the TM hard drive and not over written. Any tips?