Can't retrieve emails, and phone messages

I can't retrieve my phone voice mails, and all emails from myaccounts; gmail.com., sbcglobalnet. com., and yahoo.com.

This has? screwed up everything in my business and personal life!

I have followed all instructions from recommended,but nothing works. AT&T,Exfinity, and Yahoo, seem to be causing the problem. Can anyone tell me what's going on and how to fix this