It depends on the operating system. On Windows (this goes all the way back to the DOS days, methinks), deleted files are simply marked by the operating system as free space. Their entries in the file allocation table (or journal, if you're using NTFS) are still there and can still be read, until they're overwritten. There's also the chance of the actual data the file held being overwritten by normal OS operation and/or defragging. If you get to a deleted file early enough, yes, you can retrieve it in its entirety, but if its been a while, then the file is likely unrecoverable.