World was set to FLAT LAND and all of a sudden while building a huge wall of water and land is now on my world around the flat land that I was building on.

World was set to FLAT LAND and all of a sudden while building a huge wall of water and land is now on my world around the flat land that I was building on. I have tried everything to get it to go away. Its like the settings have reverted back to the normal landscape around the town that I was building on the flat land. Can you fix this without me loosing all of my progress on my flat world??