More info required. Such as - what is your OS? if XP have you emptied the recycle bin, could be thats where they are. If not and you've saved much since you 'lost' them the chances are not good. You might be looking at a 'Techie' service.
Where have you lost them from? I messed a cd and lost some a while ago and found a prog called ISobuster very good. If on HD you could also try PC Inspector File Recovery. I suggest you let your fingers do the virtual walking and search on something file recovery to see what comes up. Best of luck and don't despair yet!