Save loss

I ran into a problem. We created a shared world and were playing together. Yesterday I logged in alone and spent a lot of time building a base. But today, when my friend entered the shared world, the base I built was gone — as if I had never played or built anything. At the same time, I can’t enter the world anymore myself. From the screenshot, it shows that the last saves were during the day, but I played most of the time in the evening.

Could you please tell me what I should do? How can I enter the world and restore all the saves? Thank you!