song could not be located

i'm coming to mac from a pc and between trying to figure out whether to keep my itunes library on my laptop or my desktop machine I seem to have kludged something.

They should all be on my desktop but when I play a song I sometimes get a "could not be located" error with a prompt that asks if I want to locate it. The locate prompt seems to bring me to two folders in the library (likely in the iTunes folder I guess).

I am not sure but I /may/ have deleted the wrong files when I manually went in and started to delete duplicates? Is this possible? Perhaps one file was showing up as not linked but I could see it and I accidentally deleted the song that actually had data in it??

Anyway, is there a good way to get back to a full library without re-importing 100's of CD's or going one by one and locating each and every song?

Thanks for any expert guidance. I'd love to get this one to stop moving...

Thanks