Do your correspondents have the correct address?
If they try to send you some e-mail, what error message do they get, if any?
When logged into your account:
Do you see any number beside the "Inbox" text? It looks like "Inbox (x)" if you have some messages waiting.
Click on "Inbox" to go to your inbox. (on the left, just under the coloured band)
Check your "Junk" folder. Maybe you only received SPAM... or the legitimate e-mails you receive looks to much like spam.