Did you try reconfiguring outlook in your machine and check if it works fine?
Are you facing this issue only in your machine? Try configuring Outlook in different machine and check if you are able to recieve emails.
Make sure that you are using the correct Mail Client settings:
> Incoming mail server (POP3/IMAP server): mail.yourdomain.com
> Outgoing mail server (SMTP server): mail.yourdomain.com
> Username: the full e-mail address like firstname.lastname@example.org
> Password: If you are not sure what your email password is we strongly recommend that you reset it from your cPanel > Email Accounts.
in which email account you are facing this issue? I mean is it corporate email account or free email account (eg: gmail, yahoomail, hotmail etc..)
Check if you are able to recieve email in Webmail.
If it is a corporate email account, you may also have to check with email Quota.
If the inbox has exceeded the limit, you may not be able to recieve any email. and certainly you may have to delete some messages from your inbox from the server( or webmail)
Please get back with sufficeient information so that we can troubleshoot your issue and help you with the same.
Thank you :)