You had 800 photos in PhotoStream.
You had the phone rest and restored.
You can no longer see the photos in the photo stream.
In fact, the photos that WERE in your Camera Roll are still visible, but no others?
Correct?
Try this:
"I don't see photos in Photo Stream on my iOS device
Check the following:
From your Home screen, tap Settings > iCloud > Photo Stream, and make sure the slider is set to the ON position.
From the Home screen, tap Settings > Wi-Fi, make sure the slider is set to ON, and that your device is connected to a wireless network.
Ensure that Camera app is closed on the device where you took the photo. Photo Stream will not upload photos from an iOS device until the Camera app is closed.
Ensure your iOS device has not fallen below 20% battery power. To preserve battery life, Photo Stream downloading and uploading are disabled when the battery reaches this threshold. Downloading and uploading will resume once you charge your device, and the battery charge is greater than 20%."
Also, after this, try taking a photo, closing the camera app, and then checking your photostream, did any new photos appear?