Not receiving E-mail either by client or webmail

I'm having a major problem trying to get my e-mail. I know there has been e-mail sent to my e-mail address, but it seems I cannot receive any e-mail whatsoever, even if I check it through webmail. I sent myself a test e-mail to the address in question, and it's not arriving at all. This is a problem that had just started happening all of a sudden. I did not make any adjustments to my cpanel settings, nor did I change anything in my e-mail client. The account is obviously still in good standing. I do not receive any error prompts telling me the account is inaccessible. It's like checking into an empty inbox...but it's not empty. I have at least four or five e-mails in my inbox that are just not getting to me. I checked my default e-mail address settings, my SpamAssassin settings, pretty much anything that can prevent my e-mail from being sent to me, and I should be able to receive e-mail, but I'm not. I have important e-mails that I need to have this inbox capable of downloading my mail again. If anyone can help, please respond. Thank you for your time.