Let a balloon in the Space means space having no air or any external force, a balloon is filled with a higher energetic particles of gas, the structure of the balloon is just like a Earth,particles of the gas in the balloon is applying the force on the wall of the balloon in every direction and with equal magnitude! (there is no any gravitational force)! tell me the status of the balloon means it will move up or down or right or left ?
The key is in your first statement: no external force! Newton's 2nd law is F=mA so if F=0 then A=0 (the balloon and gas inside have mass not equal to 0). So the balloon is definitely not accelerating.
Is the balloon moving? Two possibilities exist: If the balloon was initially moving and there are no external forces on the balloon then the balloon is still moving with a constant velocity. If the balloon was initally at rest and there are no external forces then the balloon is still at rest.
What can be said of the balloon is that it is in equilibrium.
What goes on inside the balloon is immaterial because the internal gas is randomly hitting the balloon walls in every direction and with no unbalanced force on the balloon structure.
There are two ways to make the balloon move. If an external force acts on the balloon it will accelerated and the balloon velocity will change. The other way is to allow gas to escape from the balloon. The escaping gas creates a force on the balloon and accelerates it much like a rocket is propelled.