Photoshop cs4 help..

Ok i just got so fucking mad today, I was cutting a render, like the best ever. I had another thing open i forogt what yo ucall it It was 500x500. So as soon as i was done i copyed it to the other thing And half of the guy was cut off. so i pressed CTRL+T and tryed to move it, but it was half. his one arm was there. but in the half it was cut. its been happening to me alot. the render will be cut off on the side. i will go to move it and ite actually cut in half. Help would be great.

ctrl alt z = undo do that 10 times

I kept pressing ctrl alt z but noting happened.