Can’t receive emails in Outlook

I am using Windows XP home and use outlook express for email purpose. I am facing a problem that I can send mail to anyone but unable to receive the emails. My computer is connected with LAN and it did not show any error messages to me regarding connectivity.
While my emails are available on my email server. But I want to fix it and want check and organize my E-mails in Outlook express. Kindly tell me how to resolve the problem?
