Creative and adventure

I was playing with adventure game mode and then I went to the creative game mode but then I realized even though I was in creative, I couldn't build or break anything. I checked my operator abilities, I was switching them on and off back and forth and going back and forth to leaving the game and coming back and switching game modes and even created a copy of the world. Everything I tried, I was not able to build or break anything, and the bad thing is, this Minecraft world is a world that I am most proud of, and now I have to delete it after all of this hard work Andy now I can't build or break anything, even in the creative game mode