Car stereo?

i installed my car stereo and forgot to hook up the antenna cable how can pull the radio back out so I can input the cable in?

Ok, so you say you have installed your stereo. My guess is that you have got an aftermarket stereo in. If you do, This is what I did here recently when I could not get it out using my hands.
Take off the boarder around the face plate take face plate off 1st . Then use a flat head screw driver and place it in the side of your stereo. Easlly prop it, to loosin it. Do the same to the other side. sooner or later it'll come out.

Aftermarket stereos typically come with two hooks/tools that you may slip alongside of the player and slide out the stereo. may have to purchase a antenna extension if it will not reach. Owner's manual will tell you how. Good luck.

What kind of stereo, in what kind of vehicle?