Is there any way to re-download Photo Stream photos on a PC/Mac?

If I accidentally delete a photo from my Photo Stream (or get a corrupted disk or lose a laptop) and later want to recover that picture from the online Photo Stream that has my pictures stored for 30 days in full resolution, how do I do that?

I tried turning the Photo Stream on and off, and it does not download the existing pictures again. If the photos are being stored for 30 days, it would be a natural thing to want to re-download on-demand. The current way it works seems like the photos are stored for 30 days as long as any one registered device has not downloaded, but once all "registered" devices downloads it, it is removed. In this context a registered device is one that was signed in to iCloud BEFORE a picture is taken. Is this correct?

For the PC the way I got it to redownload the photo stream is first go to Control Panel then open up iCloud control panel.

Turn Photo Stream to off and close the iCloud control panel.

Just as a precaution, rename the old Photo Stream folder just to have a backup of what was in there before. This is up to you.

Then go to C:\Users\yourusername\AppData\Roaming\Apple Computer and rename the MediaStream folder to something like MediaStream-old.

Then go back to Control Panel, open up iCloud control panel and renable the Photo Stream.

If you chose a custom download location for Photo Stream then you have to choose it again. The photos should start coming in, but just remember it will only grab the last 1,000 photos you have taken.

Thanks.

The only way I see so far that you can do this Directly is from a Mac. By using iPhoto or Aperture to copy (drag N drop) the photo/s from a album back into Photostream.

From an iOs device. Indirectly.

if You have iPhoto you can select the photo and use the share button to add it to Camera Roll. This will then add it to you normal iOs device photos.app and from there it will go into Photostream. It does mean you will have a dupe in the Camera Roll. But I cannot see away to add it back to Photostream directly in photos.app

The simplest way to re-download your entire stream is to set up a second account on a Mac computer and fire up a clean iPhoto library.

You can turn on Photo Stream syncing and have it automatically import all photos. Once that is complete, you can export them to a shared folder or external drive and then delete the temporary account and all of it's data.

On your main account you can then turn on Photo Stream or not, but import the missing photos as desired from the export.