Set wrong screen size….can't see posts….HELP

Help….I was logged in as administrator and working on the dashboard deleting spam under “all Posts”. To make it more efficient I went to screen settings and changed it to show 400 per page rather than the 250 it was already set on. Now when I click to see All Posts, I get a an “Internet Explorer Cannot display the webpage”. I assume it’s because I set the number to show too high since that’s the only change that was made. I can’t bring the screen back up to change the 400 setting back to 250…is there another way to do it? right now I’m unable to see the posts from the WordPress dashboard.