Hi Rhua,
Webpage as in Browser version of the game? How long has it been, just recently today - or has it been awhile? If it was today, it might just be a typo on the login.
But if it was awhile ago, some accounts are "deleted" (de-activated) after a certain amount of days of inactivity. But you might be able to still get it recovered.
Either way, to inquire about recovery, open up a support ticket.
Click this link >> http://support.bigbangempire.com/
And then on the left side, click: OPEN NEW TICKET
Fill out the form to the best of your ability, give them as much info as possible, select I AM NOT A ROBOT and click on SUBMIT TICKET.
Write down the TICKET NUMBER, so you can followup with the recovery process.
Best of luck getting back in to the game...
-TB
.