when you delete a file, as a million ppl have said before me, its not really deleted just the reference to it in the filesystem table is removed and that space where the file was becomes free to be reallocated should it be ever be needed.
how you get back these supposedly deleted files is up to you, theres no doubt several windows apps thatll do it.
keep in mind that if the space where the file was may have been overwritten rendering that file unable to be recovered, by you.