My worlds were changed to creative

When I went to make a new survival world on mcpe I had left the world so my phone could charge. When I checked back it said Creative Long Ago and when I was about to delete it it said Seed: 0. Then I went to my survival map and looked for some diamonds and left it and when I checked back It said Creative Long Ago and Seed:0. I then loaded back up and my world was turned into a creative world. Everything was the same my house and creations were still there ,but I noticed that I didn't have my Iron Pickaxe, Cobblestone, and wood in my inventory. I need this fixed fast, this was the first world I found gold and diamond on.