Toro zero turn with kawasaki engine

Hi my step dad had a stroke and 2 brain surgeries so he can't read, write or talk anymore… He was a mechanic and electrician in the Air Force for 20 years and the Superintendent for all of the country vehicles here in Georgia for 20 years also he drove the Toro zero turn into the pind? and we have fixed everything except it won't go forward or backwards any ideas he keeps trying to tell me some but as far as this goes I'm stuck…..I'm a woman sooooo be nice on the comments I've almost got this thing fixed just but him screaming, yelling, and pointing.? Thank