I won’t point the finger and cry plagiarism, but I will say this: you do like long, drawn out sentences, don’t you? Use a comma or a period once in a while. It causes a lot of confusion and I actually found myself giggling at points which doesn't bode well on your story.
You have a problem with repetition. For example, you write that every window for a mile around the Potter house is shattered and then you write that the window in the nursery is no exception. That point was already stated, there was no reason to repeat it, especially directly after the first mention of it. Furthermore, you write that Alex was screaming in pain. The next sentence states that all was quiet except for Alex’s screams. Not only does the end of this sentence negate the beginning of it (since the baby is screaming that means it is not quiet), it also repeats the previous sentence.
There’s a problem with this bit:
“James and Lily rushed towards the house panicking when they found the body of their babysitter a daughter of an order member. James ran to see if she was still alive while Lily ran up the stairs screaming for her babies to be alright. Once they reached the door they found it shut but unlocked. Throwing it open James leapt into the room with Lily right behind him both scanning the room with their wands.”
You had James checking on the babysitter while Lily ran up the stairs. Then you had James leading the way into the babies’ room. You specifically stated that James did something while Lily ran up the stairs. By all rights, he would’ve been far behind her. Even if James was a fast runner, at the very least, he should have been two steps behind Lily.
“Instead of the evil snaked face man and their dead children as they had expected to find, they were instead met with an empty room. The cribs were still intact and one of them had painful whimpers coming from it.”
If two cribs were in the room with one baby crying, why was it empty? It clearly was not empty. You should have said that there was only the two cribs with one baby crying.
I would suggest getting a beta reader, after you reread your work that is.