I am not receiving my emails from my contacts

With this kind of issue, you may need to investigate what''s causing it. Here the things that you can check:

* Did you setup an filter or rule on your account?
* Check Junk Mail, probably their mails are being treated as spam by the spam filter that yahoo is utilizing.
* Ask your friend if they are receiving any bounce back message or non delivery report every time they send a message.

You can also do your own test, if you have an alternate email address you send a test message to that email address that is having issues right now and see that will happen.