all my photos gone suddenly

I dont usually go to icloud.com to check saved photos and videos but yesterday I checked my saved photos and video to find something that I needed but it was all gone, deleted automatically. omg what happened . I opened one email from apple 2months ago that my photos will be gone within few days blah blah,... of course I did not check my email for a long time and my photos were gone completely. What is wrong with icloud? and how can I get them back??? Please let me know please please. I am dying here