To see or dream that you are in a wheelchair, suggests that you need to stand on your own two feet and stop depending on others. Perhaps you are feeling helpless. Alternatively, it indicates that you are literally letting others push you around. You need to start standing up for yourself.
If someone is able-bodied in real life, but you dream that they are in a wheelchair, then it suggests that he/she is in need of your help. They may be afraid to ask you directly and have been dropping hints which your unconscious may have picked up on.