Website isn't working

SO recently I’ve been working on an online newspaper for my school and we’ve hit a few bumps in the road, but we’ve been able to get over them and continue. We just started getting our website how we wanted it and now we were trying to chsange the URL when it just stopped working. We entered th new URL we wnated and the entire website got screwed up and it won’t let us log in to edit it now. We need help because we have no idea what to do..