I CAN'T ACCESS MY EMAILS EITHER THROUGH THE OLD EMAIL ADDRESS OR WEBMAIL

Hi I hope somebody can help me.  This morning I was on my emails without any problems.  After doing an online course this afternoon I have been unable to retrieve my emails using either the old email address or through webmail via my account page.  This has lasted for over 6 hours.  I have turned my modem & computer off and restarted both of them several times to no avail.  I don't know what else to do.  All the buttons that need to be lit on the modem are all lit.  Any other suggestions.  Thanks in advance .