This is convenient for making backups of your digital information so that more files can fit in a USB key, CD-ROM, DVD, or Blu Ray. Certain formats shrink files without sacrificing the quality of the content. The all-purpose Format Factory free download can also reduce the size of heavy files. You'll get your files back if you change their format into one your OS can recognize or that you can open with an application installed on your computer. If they do appear, you will see a blank box or a question mark where the file icon should be. Your files are not erased, even if you can't see them on your file explorer.