If you downloaded from your iDisk using a browser then the files would land up in your download location as set in the browser - by default this is usually the Downloads folder in your Home folder. The file names would be whatever they were on the iDisk. If you changed the download location then they would be where you placed them. In Safari Preferences>General this is set in the menu 'Save downloaded files to'.
There is no possibility of re-downloading anything.