My WHOLE world was ERASED!!??

So today, i turned on my aternos server for queue. My world always used 1.11.2. When it was finished I tried to get onto my world, but it said I had to be on 1.12, but on the site it said that my server was still 1.11.2, even when i refreshed it. When I change into 1.12, I get onto the server and ITS A WHOLE NEW WORLD???!!!! everything me and my friends created was gone! When I was on my server, still in shock, I was suddenly disconnected from it and my server turned offline. When I come into my server, shouldn't it stop the countdown to going offline? I haven't saved my world or anything because I thought Aternos was responsible for that I am extremely angry because we had quite a bit of progress on that server and if there is any way to retrieve it back, please tell me.