I have a LA 175 lawn tractor. When mowing the yard I noticed the rear tire was flat. I disengaged the mower and drove the tractor into the garage, removed the tire, installed a new tube, mounted the tire and wheel assembly and finally started the tractor. When I engaged the transmission to move forward there was no movement in forward or reverse and to top that when the tractor is running if I engage the mower the tractor immediately shuts down. I disconnected the belt that controls the deck blades, yet the engine continues to die when the switch is employed. Initially the problem was a flat tire and suddenly grown to numerous mechanical issues. Frustrated....any help would greatly be appreciated.