I am not able to send or receive any mail on my yahoo account.

How do you access your Yahoo mail? Is it via the browser (www.yahoo.com) or via MS Outlook?

If you're having a problem of sending/receiving emails while using the web browser, you may want to delete old and unnecessary emails. You could have reached the storage limit of your email account.

But if your using an Outlook, you need to double-check the account settings. Make sure that you have the correct user name, password, incoming and outgoing servers, incoming and outgoing ports.

If you setup your email account using the POP protocol, you may use these server ports:

Incoming: 110 or 995
Outgoing: 25 or 2525, or 587, or 465 (SSL)

For IMAP:

Incoming: 143 or 993
Outgoing: 25 or 2525, or 587, or 465 (SSL)

If the same problem occur, you may try to delete your account and recreate it. Please bear in mind that if you deleted your account and recreated it, some emails may no longer appear or get downloaded.

Thank you and good luck!