It isn't always possible for us to know exactly why some things happen to us. We need to remember, however, that God doesn't cause evil -- and even when something bad happens to us, He can still bring good out of it, if we'll let Him.
And that's what I hope you'll focus on -- not why this accident happened, but what God wants to teach you through it. I don't know what that might be, of course, but God does, and I hope you'll ask Him to show it to you. Let the ancient prayer from the book of Job become yours: "Teach me what I cannot see" (Job 34:32).
What may God want to teach you through this experience? For one thing, He may be wanting to teach you about the brevity of life, and how easily it can be lost. How, then, will you live from now on? Will you live a life of self-centered indulgence -- or will you live for Christ and His will? If you have never done so, commit your life to Jesus Christ, and then begin living the way He wants you to live.
But God also may be teaching you what it means to live for others, and not just for yourself. Many people come away from an accident or serious illness with a new appreciation for their families, or a new determination to live each day to the fullest. But I urge you to go beyond that, by asking God to help you find ways to serve others for Christ's sake.