All my emails are gone. Cannot access emails or send emails.

All my emails are gone. Cannot access emails or send emails.

When I click on the email icon I get a screen with the headings etc. for the mail page but no emails...nada!
I also cannot send emails.
I saw in the forum to check with the host. I did . The host has not blocked zoho.
Please help me...I need to access my email ASAP.