Walaikum Assalam.
I can feel you. Either way, I would suggest you don't worry about such questions please. Those aren't coming from a stable mind but from the Satan whispering to you such questions.
I will however try to answer all and hope you get some help from them.
1. Who created God?
Allah clearly mentions in the Quran in Surah Ikhlas, Chapter number 112, verse number 3, He begets not, nor was he begotten.
Allah is neither created, nor will he be destroyed, or die.
For the sake of argument, even if I agree that God has a creator, then you'd ask, who is the creator of that creator? And again, who is the creator of that creator's creator? And the question goes on and on and on until infinity.
Hence simple logic says that God always existed and will always exist. Moreover, this question arises because we tend to believe that there is a past, present, and future. However that not the case. Don't bash me, but if you do some advanced Physics, you will come to know that there's nothing like time. No past, no present, no future. Everything is in a moment of NOW. I am currently doing a research on Physics - Time and most of the experts have come to a conclusion that there's nothing like Time. What we use in our daily life is for our ease, it's just an illusion. I know it sounds like am being a moron, but trust me, am being honest. Hence like I said, Science proves that there's nothing like time, so there's no question of what came first and when will it all end. No, God was always there and will always be there. Hence the concept of Heaven and Hell, eternity. I have seen some people here ask that will it not get boring in Paradise? Nah it will not. Because you cannot use the Physics of this world and compare it to Jannah. The physics of Jannah is heavenly and totally different. Like I said, there's no past, present and future, hence no reason why you will be bored. Hence also logically you know God was there, is there, and always will be there. No beginning, no end.
2. Why did Allah create this world?
Well, He is the Creator, a Creator by definition creates right? So as He is a Creator, He had to create.
. If He doesn't create, then why is He a Creator? Lol, I hope you get it, simple answer there.
3. How did He create them?
Well, that's deep. Do you know how a fly is created? A house fly. Do you know? We don't. So I believe we should rather think about small stuff first, then imagine the big. Allah says BE and it IS. So yah, for Him it's a piece of cake, for us it's something great because we can't make. There are 2 types of makers. One is like us, who makes something from something. Like you cut a tree, take wood, chop it, make furniture.
2nd type of maker is making something from nothing, that only Allah can do, we cannot.
And remember, science doesn't answer why, it answers how stuff works. It doesn't answer how stuff was made either. It says the Earth revolves round the sun but it doesn't know why the Earth should revolve round the sun, making 24 hours day, sustaining life, but it does support life, amazing right? Science sees no reason why. So if you're in to science and have basic understandings of it, you'll come to know that we humans deal with how stuff works and not necessarily with why that way. Why 2+2=4, why not 8? The answer is, we don't know. Neither is it necessary. It's just the way it is. We either accept it or reject, intelligent people accept.
.
4. What is Earth wasn't there and nothing was there?
To answer that, you first need the situation to be present. If I ask, what if you weren't ever born? That's a silly question because to realise that or know that, I have to go back in time and make you "not to be born ever", which is ridiculous and unscientific and impossible. Hence the question itself is illogical. If you can make the world disappear and nothing appear, only then can you know what would have happened. Till then, you can only uselessly wonder.
Hope these helps. And I hope you realise the questions you asked, or aka, the questions which Satan makes people think of, is unscientific, and irrelevant, and silly, ridiculous in the highest degree.
.
Hope this helps eh... Good day.
eace: