As far as the movement of the mouse, most mice have a horizontal and vertical roller that the ball moves in one or the other direction when the mouse is moved. This roller is attached to a wheel that has one of many types of sensors to determine how much and what direction the mouse was moved. Other types of mice use a Led and led sensor between which a slotted wheel that is connected to the roller. The wheel slots pass and block the light creating a signal that shows distance and direction. Repairs to mice are not common.
Some Engineers replace switches and clean or adjust the wheels and rollers.
Most just replace the mouse, it is cheaper. Cursor does not move left or right. Led not working, led not close enough to led sensor or wheel, contacts dirty on contact type sensor, bad cable , bad logic board. Left or right button inop. Switch has failed, or is dirty, bad cable , bad logic board.