You may be lucky and find a very sympathetic agent at check-in that will allow you to board BUT that is probably not going to be the case. Cruise lines are now quite diligent about your cruise documents matching your passport, birth certificate, etc. Contact your travel agent immediately, so that new documents can be issued to you. Some cruise lines will charge a fee, some will allow the change and not charge you if you pick up the new documents at the pier upon arrival, and in some cases your travel agent has a working relationship with someone at the cruise line that can rectify the matter. But, in any case - I would not take any chances - make sure the cruise line has been contacted ASAP.