trying to reset the windows to their original positions.

i dont know how i moved the windows around to the places their in now, but i did,  i'm watching a teacher using Pr and his windows are in the original positions and mine are'nt, so what i would like to know is does any one know how to put all the windows back in the places they are in when Pr is first downloaded so i can follow my teacher easyer and not get mixed up trying to follow him because my windows ara'nt in the same places that his are in. can some one PLEASE HELP me out with this problem.