Chosen Solution
About a week ago I stopped receiving mail to my iphone. I haven’t encountered any other problems as yet, but this problem is a biggie.
You haven’t specified your email provider, but if you’re using a service such as GMail, it might also be worth checking to see that POP/IMAP (whatever you use) hasn’t been accidentally disabled in your GMail settings. (You’ll need to login via a web browser to get to these settings. I don’t recall at the moment if they’re available via a mobile web browser, so you may need to be on a desktop/laptop.) I mention this because I accidentally disabled IMAP once while poking around with some other settings in GMail. It took me ages to figure it out. If you provide more information, maybe we can give more pointed suggestions. Good luck!