I cant find my music files?

I have Sonic as my music software. I have spent ages transferring all my cd collection onto it but when I go into my computer I can't find the files. They only seem to be in Sonic, they all play and download onto my MP3 ok. I have ran searches in hidden files etc but I cannot find them. Music I had stored on WMP is in the my music files but not anything on Sonic. Where can they be and how do I find them. I know that they must be on the computer some where!