Recently I created a mansion on Minecraft pocket edition and blew it up accidentally but I think my level.dat_old still has the mansion. I think it would be the same file type as level.dat when code and I was wondering if there was a way to copy the code over level.dat. I do not own a computer, I just have my android phone.
There is not any tool for minecraft nbt editing that can run on Android. But there are great tools for PC, like for example the Minecraft Universal Editor.