can you recover deleted photos in iCloud?

If you mean photos removed from photo stream, unfortunately no. If you mean photos deleted from your camera roll, they are supposed to be included in your iCloud backup (although unfortunately not all users report success in getting them back). If you made a backup while these photos were still in your camera roll, you may get them back by restoring this backup to your phone. (Note, restoring a backup will revert all settings and data on your phone to those contained in the backup, not just photos.)

Hi, do you mean once deleted from icloud photo stream, there is no way that we can recover it? Can we contact Apple server to restore it?

Unfotunately, No.