Exchange password incorrect. I can't enter the domain info because I can't do anything on my ipod

my school requires that all students change their password to their exchange accounts every few months. When I did so, my ipod stopped working. Now everytime I turn it on a 'password incorrect' box pops up and I can't do anything else on it. I put in my new password and it doesnt work, when I put in my old password it doesn't work and when I hit the cancel button it just pops back up. It is completely useless. So I went to my schools website and all they offer is the domain info, but I can't even try that because I can't escape the "password incorrect" box. What do I need to do?!?!