What actually goes on inside of person with a damaged brain? Are they are able to consciously think like someone who has a perfectly normal brain?

My question includes all forms of accidents that cause brain damage but I definitely wanted to know more about stroke victims? Why can a stroke completely change a person? Why does it usually confine them into a wheelchair? You know how you have that little voice in your head that usually helps you through rational decisions, do they not have that anymore? Thanks guys 
When a person has a stroke, the damage can be so extensive that the neurons in the brain can no longer communicate with other neurons to send messages throughout the body [1]. As a result, the stroke survivor can experience physical symptoms like weakness on one side of the body or vision impairment [1]. Behavioral symptoms like overconfidence or impulsivity may also be present [1]. And the stroke survivor may experience language or speech impairment, as well as thinking and acting responses that are slower than normal [1]. Fortunately, the brain does have the ability to heal itself through a process called neuroplasticity [1, 2]. Neuroplasticity allows the brain to form new neural pathways and transfer functions that were once held in damaged parts of the brain to new, healthy areas [2].
Many traumatic brain injuries, such as strokes and car accidents, can cause personality changes as well as physical symptoms [2]. Often, doctors can predict what symptoms a person may have based on the area of the brain that was damaged [2]. Brain injury can take a long time to recover from. Some people may never fully return to their cognitive function before their injury [3]. A stroke is an injury to the brain that can cause bewildering changes in a person's emotions and behavior [4]. Stroke survivors' brains have been injured, and the behaviors and emotions they display are reflections of that injury [4]. Loss of a person's former identity can result in depression, anger, and frustration [4]. Another personality change that occurs after a stroke is impulsiveness. This is characterized as the inability to think ahead or understand consequences [5]. Post-stroke depression can also occur and has multiple causes, including physical limitations, health worries, brain changes, and delays in treatment [6].