In general, an airplane requires air moving over its wings in order to generate lift and stay airborne. The lift is primarily generated by the forward motion of the airplane through the air. Therefore, in still air, an airplane cannot fly or maintain altitude.
While it's technically possible for an airplane to fly with a strong headwind, it cannot fly backward relative to the ground. The headwind increases the airspeed of the aircraft, which can help it generate more lift and maintain its position or fly at a slower groundspeed. However, the airplane will still be moving forward through the air, even if its groundspeed is reduced or even becomes zero.
Flying backward relative to the ground would require the airplane to generate enough thrust to overcome the drag and move in the opposite direction. Commercial airliners and most conventional airplanes are not designed to generate thrust in a direction opposite to their forward motion. They are optimized for forward flight and rely on engines and aerodynamic configurations that facilitate movement through the air in a forward direction.
There are some specialized aircraft, such as helicopters and VTOL (Vertical Takeoff and Landing) aircraft, which can hover and fly backward by redirecting their thrust or changing the orientation of their rotor blades. However, these aircraft operate on entirely different principles than fixed-wing airplanes and are not affected by the same limitations.