Does anyone know if i can replace the antenna mast only on a power antenna or do I have to replace the whole thing?

I can hear the motor working, but the antenna does not extend due to the fact that someone bent it .

 

Sure. That's why they sell the masts by themselves, about $20 or less. Easy job, too: loosen the nut, turn the radio on, and it shoots the whole thing out. Then just feed the new cable down the hole and have someone else turn the radio OFF, and it should suck it right down, then just tighten the nut... That's how it SHOULD work.