Dear babar,

Try to put a 10k resistor from collector to the base.

remember, this resistor should directly connected to the transistor's base, otherwise your logic circuit may destroy. better try to apply input from direct +5v supply with a resistor rather connected to real logic.

Typically when transistors are used as voltage amlifier, it is always recommended to use as invertor (output taken from collector), not emmiter follower. in this case you will require two transistors in series. First transistor will provide inverted voltage amplification and second will invert and return the signal back in its actual logic.

Rauf