こんにちは。下記の方法でいかがでしょうか。私はこれで復帰しました。
1. Open Task Manager by pressing CTRL, ALT, DELETE or right clicking the taskbar and clicking 'Start task Manager'.
(=>タスクマネージャを立ち上げます)
2. End the two tasks ApplePhotoStream.exe and AppltPhotoStreamDownloader.exe
(=>上記二つのタスクを終了させます。)
3. In explorer, navigate to the following path: C:\Users\\AppData\Roaming\Apple Computer\MediaStream\ (For example, I open Explorer and click my username on the left. The long way round is Computer>Hard Drive>Users>Your User Name>Appdata and so on. You may need to enable 'Show Hidden Files' in Folder Options.
(=>フォルダオプションで隠しファイルを見えるようにして、C:\ユーザ名\\AppData\Roaming\Apple Computer\MediaStream\を開く)
4. Delete everything in that folder. They won't delete if the two Apple tasks are running. Apparently these are a local cache of what has been synced.
(=>上記フォルダ内の全てを削除する。もし上記2のタスクが走っていると削除できません。)
5. Open the iCloud Control Panel and make sure the checkbox for 'Photos' is ticked.
(=>iCloudコントロールパネルを立ち上げ、「写真」チェックを入れる。)
http://lowrescontemplation.blogspot.jp/2014/02/icloud-photo-stream-not-syncing-to-pc.html