Excellent advice (yes, really!) from Hopkirk!
Otherwise a bit more information might help here? Are you using your iPad or another device? If you're using your iPad, are you accessing your email through its dedicated email app, through a different email app or via your web browser? If it's via an email app you should still be able to access your emails by opening your web browser (which is probably Safari), going to the web site of your email provider and logging in there. That will at least provide a temporary workaround while you're trying to fix your main problem.