Worlds deleted after playing off wifi

I had hooked up my Xbox in a different room of the house and played it offline ( my ethernet cord was no longer connected to my Xbox and I did not set up a wireless connection). After playing for a bit I saved and quit out of one of my main worlds and went to go move my Xbox back and connect it to the ethernet cable. I got on Minecraft the following day to see that all the worlds that I had played on the day before have all deleted. One of them being a world that I have worked on for the past 4 years!!!!!