I'm a F-1 Visa student marrying a US Citizen ... if I'm out of status Do I have any trouble?

Hi .. I came to New York with a F-1 student visa and I want to married a US citizen. We already have all the documents that inmigration ask to make the petition but when we went today to submit the documents they told me that My visa is already expired and as a result my fiance can't ask for me .... I'm really so confused about this ... Mi visa is expired but my I - 20 is untill 2011 .... the true thing is that I didn't study this semester because I was sick and possibly I'm out of status ... so how can I make a reinstaiment ? what can I do ? there is any law that says that F -1 students can't marry if they are out of status ?
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