I don't know why God allows things like this to happen to us -- not fully. Some day, when we get to heaven, we will know -- but until then, we simply have to accept them and adjust to them as best we can -- with God's help.
After all, life isn't always the way we wish it were. I'm an old man now; by the time you read this, I will have passed my 91st birthday. I can't do everything I once did, and occasionally that frustrates me. But then I remember how good God has been to me, and His promise to be with me every day of my life. His Word is true: "Be content with what you have, because God has said, 'Never will I leave you; never will I forsake you'" (Hebrews 13:5).
Don't dwell on what you can't do; thank God instead for what you can do, and for the measure of health He has given you at this stage of your life. After all, your stroke could have been much worse. The Bible says, "Give thanks in all circumstances, for this is God's will for you" (1 Thessalonians 5:18).
The real question, however, is this: What is God trying to teach you through this experience? Perhaps you've never thought about eternity and the fact that some day you will die and face God. Whatever your spiritual condition, open your heart and life to Jesus Christ, and seek His will for the rest of your life.