What was there before the BIG BANG occurred?
According to theory before BIG BANG there was nothing, the Space and whole Universe didn't exist, there only existed a tiny mass(not visible normally) full of energy . BIG BANG occured just of a sudden when that tiny mass bursted off releasing a lot of energy which created the space, which began expanding and expanding. This created clouds of elements, dust particles, etc. which began on a cycle of formation of Life -> Planets -> Solar System -> Galaxy and also it's death and again reborn of it from it's fragments.