Please don't ask what is "wrong" with the person who has a disability. Ask what their condition is or why they are using a chair or cane or service dog or something like that.
I was at the mall with two friends, one who is blind and one who uses an electric scooter. The two of them were in the fitting room and I was out on the floor, looking for the correct size and color of a sweater one of them was looking for. The saleswoman came up to me and asked what was wrong with my friends. For a horrible, heartstopping minute, I thought something had happened to one of them and she had gotten hurt. Nope, the salesperson just wanted to know why one friend had a dog with her and the other had a scooter.
And I was out with my 10 year old nephew last weekend. He has a spinal cord injury and uses a power chair. Someone came up to me and asked, "What's wrong with that kid?" 1) He can hear you. And understand you. There's nothing "wrong" with his brain (as he will cheerfully inform you). He doesn't need to think that there is something "wrong." He has enough issues after half a year with the school aide from heck. 2) This is how he is. How he was born. He isn't wrong. He is affected by a genetic syndrome that caused certain orthopedic issues. He is not "wrong" or "bad." He's "different."
Asking what's "wrong" can be very hurtful.