All Muslims believe that there is only one Creator. The following question is thus blasphemous (i.e. asking this question or hesitating about it makes one a non-muslim), and was asked by a non-Muslim. Nevertheless, it needs to be answered to prevent it from affecting peoples beliefs. The question that the non-Muslim asked was: Who created the Creator?
Unlike anyone else, the creator has NO beginning so the creator doesn't need a creator. Everyone other than the creator needs a creator because anyone other than the creator has a beginning. Moreover, it is impossible for the creator to have a beginning because having a beginning makes one in need for a creator, and it is impossible for the creator to need anything because he is perfect. A more detailed answer and more proofs are available on request.
It should be noted here that claiming that the creator has a beginning or has a creator is against the very basic belief of Islam and hence the above question is considered blasphemous i.e. causes the person who asks it to exit Islam and become a non-muslim, because it means that the one who's asking is claiming that the creator has a creator and he wants to know him.. If you need an answer to such a blasphemous question you can say something like: [How do you answer someone who says "so and so"?]. This way you get around asking the blasphemous question directly and falling out of Islam.